6.8: Early and Middle Republic
The period from the founding of Rome to the end of the Punic Wars is less documented than subsequent Roman history. Nevertheless, this period was the formative time during which Rome grew from a village on the Tiber to a pan-Mediterranean empire.
The process was as fascinating to consider for later Romans as for outsiders. The Greek politician-turned-historian Polybius , who spent seventeen years as a hostage in Rome and became quite a fan of the Roman military and political machine, put it simply in the prologue to his Histories , in which he documented the meteoric conquest of the Mediterranean world by the Romans:
For who is so worthless or lazy as not to wish to know by what means and under what system of government the Romans in less than fifty-three years have succeeded in subjugating nearly the entire known world to their rule, an achievement unprecedented in history? (Polybius 1.1.5)
Polybius’ question pointed to the answer that he subsequently proposed: part of the reason for the Romans’ success was their adoption of the Republican government as replacement for their original monarchy. Polybius became increasingly convinced during his stay in Rome that the Romans’ government was superior to all others in the Mediterranean at the time.
6.8.1: From Monarchy to Republic: Some Myths and Legends
“In the beginning, kings held Rome.” Thus the late first-century CE Roman historian Tacitus opened his Annals , a history of the Empire under the rule of the emperors from Tiberius to Nero. Early Roman history is shrouded in myth and legend, but the beliefs of later Romans about their own past are important to consider, as these beliefs, whether truly grounded in reality or not, determined subsequent decisions and actions of the historical Romans later on. This tendency is especially true of the Romans’ myths about the foundation of their city in 753 BCE and the kings who ruled it until the establishment of the Republic in 510 BCE.
According to myth, Rome received its name from its founder Romulus , the son of the war god Mars, and a descendant of the Trojan hero Aeneas. By linking themselves to the Trojans, the Romans were able to boast an ancient, reputable lineage, rivaling that of the Greeks, and a prominent place in the Greek heroic epic, Homer’s Iliad . Furthermore, when embarking on a conquest of Greece later on, the Romans could claim to be seeking revenge for their Trojan ancestors’ defeat and destruction by the Greeks during the Trojan War. Several generations removed from their heroic ancestor Aeneas, Romulus and his twin brother Remus were famously abandoned as infants and then nursed by a she-wolf, the sacred animal of their father Mars.
The sweetness of the story ends there, however. While Romulus was building Rome, Remus insulted the new city, and his brother killed him to avenge its honor. Later, after Romulus had completed the building of the new city with his band of soldiers, he realized the lack of women in the city, so Romulus and his supporters raided the neighboring tribe, the Sabines, and kidnapped their women.
It is telling that later Romans believed that their city was founded on fraternal bloodshed, as well as on rape and kidnapping. The stories of Romulus’ accomplishments, while not laudatory, show an important Roman belief: the greatness of Rome sometimes required morally reprehensible actions. In other words, Rome came first, and if the good of the city required the sacrifice of one’s brother, or required force against others, then the gods were still on the side of the Romans and ordained these actions.
Romans believed that, altogether, their city was ruled by seven different kings in succession. After Romulus, king Numa Pompilius regulated Roman religion and created many of the priestly colleges and positions that continued to exist thereafter. The seventh and final king, however, Tarquin the Proud , was known for his and his family’s brutality. The final straw appears of have been the rape of a nobleman’s wife, Lucretia , by the king’s son. An aristocratic revolution ensued, which appears to have been largely bloodless, if Livy’s account is to be trusted. The royal family was expelled from the city, and two consuls were immediately elected to govern the newly formed Republic. Or so, again, Livy tells us, based on Roman legend. The reality is likely to have been more complicated. Assuming there truly were seven kings who ruled the city, and assuming that the last of them was driven out by an aristocratic revolution, it appears that a period of transition ensued, as the Romans experimented with a variety of short-term solutions before arriving at the model of the Republican government that we know in the historical period. Furthermore, apparently what guided that gradual evolution of the government was the growing dissatisfaction of the plebeians, the lower socio-economic majority of the city, with their exclusion from the political process.
6.8.2: Early Republic: Conflict of Orders, the Twelve Tables, and Key Legislations
Roman sources from all periods, beginning already in the early Republic, reveal certain common values that all Romans held dear and considered to be foundational for their state. First, Romans had a strong respect for the past and were averse to change. Indeed, reformers had a difficult time passing their proposals in all periods of Roman history. The term for this reverence for the past, mos maiorum , “custom of ancestors” or “custom of elders,” is telling. While innovation is a revered value in the modern world, Romans believed that innovation amounted to disrespect for their ancestors. Ancestral custom, which had first made Rome great, had to be respected, and successful reformers, such as the emperor Augustus, managed to phrase their reforms as a return to something old, rather than as something new. Three additional values that are key to understanding the Romans are auctoritas , “power” or “authority;” dignitas , roughly meaning “dignity;” and gravitas , “seriousness.” Each citizen in the state had a degree of auctoritas , that intangible quality that made others obey him, but the degree of auctoritas varied, depending on one’s social and political standing. Augustus, Rome’s first emperor, would later describe his position in the state as having more auctoritas than anyone else. The other two qualities, dignitas and gravitas , were connected and reflected one’s bearing and behavior as a true Roman. Jocularity was not valued, but seriousness reflected a particularly Roman conduct and determination. It is striking that Romans never smiled in portraits. The austere facial expression, instead, conveyed their power and superiority to others, whom they had conquered.
While sharing common values, Romans were also deeply aware of social divisions between themselves. From its earliest time, Roman citizen population was divided into two orders: the patricians , defined as the descendants from the first one hundred senators appointed to the Roman aristocratic Senate by king Romulus, and the plebeians , that is, everyone who was not a patrician. The plebeians had their own political assembly, the Plebeian Council , while all Roman citizens also belonged to the Centuriate Assembly , which was responsible for annual elections for top political offices. The period of the early Republic, following the expulsion of the kings, was a time of conflict for the two orders, as patricians tried to establish a government that reserved all political power to themselves, whereas the plebeians fought for the opportunity to hold political and religious offices. Although they did not wield any political power at first, they discovered in the early fifth century that their most powerful weapon was secession, that is, departure en masse from the city, until the patricians acquiesced to a demand. While much about the Conflict of the Orders —just as anything else about the history of the early Republic—is shrouded in legend, it is possible to track its progress through the evidence of legislations that the Romans passed.
In 494 BCE, following the first plebeian secession, the Roman Senate allowed the plebeians to elect plebeian tribunes. An office that eventually was reserved for senators, it was originally merely an opportunity for plebeians to elect officers in the Plebeian Council, the assembly of all plebeian citizens, who would advocate for them. Plebeians next appear to have advocated for a public display of the laws, in order to protect the poor during lawsuits. The result was the first Roman legal code, the Twelve Tables , which was inscribed on twelve tables c. 450 BCE and displayed in public. One of the laws included was a ban on intermarriage between plebeians and patricians, showing a clear commitment on the part of the patricians to maintain the separation of the orders. It is important to note, however, that with the gradual decline in the number of patrician families over the course of the Roman Republic, most began to intermarry with prominent plebeian families.
The highest political office in the Republic, that of the consul, continued to be reserved solely for patricians until 367 BCE, when two senators sponsored the Licinian-Sextian law. The law required that one of the two consuls elected each year had to be plebeian. The phrasing of the law was significant, as it allowed the possibility that both consuls elected in a particular year could be plebeian, although this event did not happen in reality until 215 BCE. Finally, the legislation that modern historians have considered to have ended the early Republican Conflict of the Orders is the Lex Hortensia of 287 BCE. This law made all legislations passed by the Plebeian Council binding on all Romans, patricians and plebeians alike.
As historians connect the dots in the story of the Conflict of the Orders through these legislations, one trend that emerges is the gradual weakening of the patricians along with the growing influence of the plebeians on Roman government. Indeed, by the third century, a number of plebeian families were as wealthy and successful as patrician families, whereas some old patrician families had fallen on hard times.
6.8.3: Cursus Honorum and Roman Religion
The debate over plebeian access to political offices in general, and to the consulship in particular, resulted in the creation of a rigid cursus honorum , a sequence or ladder of political offices. The ultimate dream of every Roman who entered politics was to become a consul, but the narrowing pyramid that was the cursus honorum stood in his path. All offices were held for the term of one year, and, in order to prevent any one individual from amassing too much power, candidates had to wait ten years between consulships. Finally, each office had a minimum age requirement, with a special privilege for patricians to subtract two years from that minimum.
The prerequisite for holding any political office was ten years of military service. Thus, aspiring Roman politicians normally entered the army around eighteen years of age. Following ten years of distinguished service, candidates who were at least thirty years of age were allowed to run for the first office in the cursus : the quaestorship . The number of quaestors each year rose over time to twenty by the late Republic. Each quaestor was assigned to a particular duty for his year in office, varying from supervising the coin mint in Rome to serving as an assistant to a provincial governor or a consul in charge of a war.
While not officially part of the required cursus honorum , most ex-quaestors next ran for the office of the plebeian tribune , if they were plebeian, or an aedile. Ten plebeian tribunes were elected each year and were supposed to advocate for the benefit of the plebeians during Senatorial debates. Aediles—a term derived from the Latin “aedes,” meaning “building” or “temple”—were in charge of public building projects and often also sponsored public entertainment.
The next step in the cursus was the praetorship. Similarly to the quaestors, the number of praetors rose over time, until topping at eight in the late Republic. Praetors could hold imperium , the right to command an army; thus, they often served in military roles or in administrative capacity by governing a province. Finally, one praetor each year, the praetor urbanus , was in charge of administering justice in the city of Rome and keeping track of legal cases and important decisions, which he issued at the end of the year as the Praetor’s Edict.
Upon reaching the age of forty, candidates who had successfully held the praetorship ultimately could run for the consulship. Two consuls were elected annually, and this position change to “office” was the pinnacle of the Roman political career. Aristocratic families kept for centuries on display in their homes the ancestor masks of members of the family who had been consuls. Since ten years were required to elapse between successive consulships, very few individuals ever held more than one consulship, until several politicians in the late Republic broke the rules altogether. Last but not least, one additional office existed, for which ex-consuls could run: every five years, two censors were elected for a period of eighteen months for the purpose of conducting the census of citizens. While this structure of annually-elected offices was designed to prevent any one individual from usurping all political power in the state, the Senate also realized that, on rare occasions, concentrating all power in one set of hands was needed. Thus the Senate could appoint a dictator for a non-renewable period of six months in times of serious military emergency, such as in the already-mentioned case of Cincinnatus.
The cursus honorum is best visualized as a pyramid with a wide base and narrowing each step on the way up. While twenty men each year were elected to the quaestorship, only a fraction of them could ever achieve the praetorship, and a yet smaller fraction could rise to the consulship. Still, election to the quaestorship secured life-long membership in the Senate, the governing body of roughly 300 politicians—doubled in the first century BCE to 600—who effectively governed Rome under the Republic. The question remains, nevertheless: how did some men achieve political advancement while others never made it past the quaestorship? Part of the key to success, it appears, lay outside of politics proper, belonging instead to the realm of religion.
Roman religion, similarly to Greek, was traditionally polytheistic, with many myths and gods aligned to the Greek counterparts. Zeus, Greek king of the gods, became Jupiter, and was a patron god of Rome under the title Jupiter Optimus Maximus, or Jupiter the Best and the Greatest.
His consort, Hera, became the Roman goddess Juno and was the patron goddess of marriage. The Greek Athena became Roman Minerva and was the patron divinity of women’s crafts. In addition, both Venus , the goddess of love, and Mars , the god of war, had mythical family connections to Rome’s human founders. Countless other divinities abounded as well; even the Roman sewer system, Cloaca Maxima, had its own patron goddess, Cloacina.
While Romans were expected to worship some of the gods in private, often making vows to them and promising gifts if the gods fulfilled a request, Roman religion also had a significant public component that was reserved for the priestly colleges. Although not limited to politicians, membership in these colleges was at times key for political advancement. One example of this phenomenon in action is the career of Julius Caesar, whose political career took off after his appointment to the religious office of pontifex maximus , head of Roman religion. Ultimately, both public and private religion aimed at the same goal: keeping the pax deorum , peace with the gods, upon which the success of their state rested, as the Romans believed. Put simply, as long as Romans maintained a respectful peace with their gods, they ensured Rome’s success. Whenever any disasters befell the state, however, Romans typically assumed that pax deorum had been violated in some way. The gods then had to be appeased in order to end the disaster and prevent similar events from occurring in the future.
6.8.4: Roman Expansion to the End of the Punic Wars
While the legends about the kings of Rome suggest that they had significant military responsibilities, it appears that their military actions were largely defensive. Just a decade or so after the expulsion of the kings, shortly after 500 BCE, however, Roman expansion began in earnest. It is important to note here several key features of the early Roman military. First, until the late Republic, Rome did not maintain a standing army. Rather, a new army was raised for each campaign, and campaigns were typically launched in the spring and ended in the fall. The festival of the October Horse, one of the religious festivals the Romans celebrated each year, involved a ritual purification of the cavalry and originally was likely designed as the end point of the campaign season. Also, similarly to the Greek world, the Romans had minimum wealth requirements for military service, since soldiers supplied their own equipment. Finally, one significant trend to note in early Republican military history is the repeated nature of Roman conflicts with the same enemies, such as the three Samnite Wars , the three Punic Wars , and the four Macedonian Wars . This repetition suggests that, for whatever reason, the Romans did not aim to annihilate their opponents, unless absolutely pressed to do so.
It appears that the Roman expansion in the 490s BCE began as a defensive measure. In either 499 BCE or 496 BCE, the expelled seventh king of Rome, Tarquin the Proud, joined forces with the Latin League, a group of about thirty city-states around the area of Rome, and led them to attack the Romans. The result was the Battle of Lake Regillus , a decisive victory for Rome. The Romans signed an uneasy peace treaty with the Latins, but war broke out again in 340 – 338 BCE. The Roman victory this time resulted in the absorption of the Latin city-states into Rome as partial citizens.
The Latins were not the only enemies the nascent Roman Republic had to face. Romans fought and gradually conquered the Etruscan city-states to the north. One especially significant victory was over the powerful Etruscan city of Veii in 396 BCE. A legend preserved by Livy states that Romans were only able to conquer Veii after they performed the ceremony of evocation , “calling out.” Fearing that their siege of Veii was not going well because Juno, the patron goddess of Veii, was not on their side, the Romans called Juno out of Veii; they promised her a nice new temple in Rome if she would switch sides. Shortly thereafter, the city fell to the Romans. When the Roman soldiers were packing up the cult statue of Juno from her temple in Veii for transportation to Rome, a cheeky Roman soldier asked Juno if she wanted to come to Rome. The statue enthusiastically nodded her head. Livy’s history is full of similar tales of divine providence intervening on the side of the Romans. These legends show the Romans’ own belief that throughout the process of expansion, the gods had protected them and guided them to success.
While still fighting the Latins, the Romans embarked upon what turned out to be a series of three wars with their neighbors to the east, the Samnites. Each of these wars, the last of which ended in 290 BCE, resulted in Roman territorial gains; by the end of the Third Samnite War, Rome controlled all of central Italy. It also appears that, at some point during the Samnite Wars, the Romans switched from fighting in the Greek hoplite phalanx fashion to a system of their own making, the manipular legion . This new system apparently allowed more flexibility in the arrangement of the troops on the battlefield; it also allowed using both heavy and light infantry as needed, instead of keeping them in a static formation for the duration of a battle. While not much else is known about the manipular legion, it appears to have been an effective system for the Romans for much of the Republican period.
It is striking to consider that the Romans spent eighty of the hundred years in the third century BCE at war. They did not seem to have had the ambition to conquer the Greek city-states who were their neighbors in southern Italy; in 280 – 275 BCE, Rome nevertheless became embroiled in a war with Pyrrhus , king of Epirus in northern Greece, after providing help to Thurii in its dispute with Tarentum. Tarentum requested Pyrrhus’ help, and he proceeded to invade Italy. The Romans fought three major battles against Pyrrhus, the first two of which he won at great cost to his army. Indeed, the term “Pyrrhic victory” in modern English refers to a victory that is so costly as to be truly a loss. The Romans finally defeated Pyrrhus at their third battle against him in 275 BCE, showing the superiority of the new Roman manipular legion even against the phalanx of the Macedonians, military descendants of Alexander the Great himself. This victory united most of Italy, except for the very northern portion, under Roman rule.
The war with Pyrrhus was the Romans’ first serious conflict with the Greek world, but it was far from their last. The Romans’ proximity to northern Greece, in particular, ensured an intersection of spheres of interest, thus also providing cause for continued conflict. Between 214 and 148 BCE, Rome fought four separate Macedonian Wars. During roughly the same period, from 264 and 146 BCE, the Romans also fought three Punic Wars against Carthage , originally a Phoenician colony that became a leading maritime power. Culminating with the Roman destruction of both Carthage and Corinth in 146 BCE, the eventual victory of the Romans over both powers allowed the Romans to gain full control over them and their previous land holdings. Their victory effectively put the entire Mediterranean world under Roman rule.
In 146 BCE, when the Romans found themselves in control of a Mediterranean empire, they appeared to foresee little of the consequences of such a rapid expansion on internal stability in Rome proper. A critical question nevertheless faced them: how would the Republic, whose system of government was designed for a small city-state, adapt to ruling a large empire? The preliminary answer on which the Romans settled was to divide the conquered territories into provinces, to which senatorial governors were assigned for terms that varied from one to five years. The system continued, with minor variations, into the Empire.
The new availability of governor positions, however, only made the political competition in the Republic even stiffer than before. Senators competed for the most desirable positions; typically, these were provinces in which military action was on-going—since this provided the potential for winning military glory—or provinces that were wealthy, with the potential opportunity in governing them to acquire wealth.


8.13: Magnetic Forces and Fields (Answers)
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Check Your Understanding
11.1. a. 0 N;
b. \(\displaystyle 2.4×10^{−14}\hat{k}N\);
c. \(\displaystyle 2.4×10^{−14}\hat{j}N;\)
d. \(\displaystyle (7.2\hat{j}+2.2\hat{k})×10^{−15}N\)
11.2. a. \(\displaystyle 9.6×10^{−12}N\) toward the south;
b. \(\displaystyle \frac{w}{Fm}=1.7×10^{−15}\)
11.3. a. bends upward;
b. bends downward
11.4. a. aligned or anti-aligned;
b. perpendicular
11.5. a. 1.1 T;
b. 1.6 T
11.6. 0.32 m
Conceptual Questions
1. Both are field dependent. Electrical force is dependent on charge, whereas magnetic force is dependent on current or rate of charge flow.
3. The magnitude of the proton and electron magnetic forces are the same since they have the same amount of charge. The direction of these forces however are opposite of each other. The accelerations are opposite in direction and the electron has a larger acceleration than the proton due to its smaller mass.
5. The magnetic field must point parallel or anti-parallel to the velocity.
7. A compass points toward the north pole of an electromagnet.
9. Velocity and magnetic field can be set together in any direction. If there is a force, the velocity is perpendicular to it. The magnetic field is also perpendicular to the force if it exists.
11. A force on a wire is exerted by an external magnetic field created by a wire or another magnet.
13. Poor conductors have a lower charge carrier density, n, which, based on the Hall effect formula, relates to a higher Hall potential. Good conductors have a higher charge carrier density, thereby a lower Hall potential.
Problems
15. a.  a. right;
b. into the page;
c. down
19. a. into the page;
b. left;
c. out of the page
21. a. \(\displaystyle 2.64×10^{−8}N\);
b. The force is very small, so this implies that the effect of static charges on airplanes is negligible.
23. \(\displaystyle 10.1°;169.9°\)
25. 4.27 m
27. a. \(\displaystyle 4.80×10^{−19}C\);
b. 3;
c. This ratio must be an integer because charges must be integer numbers of the basic charge of an electron. There are no free charges with values less than this basic charge, and all charges are integer multiples of this basic charge.
29. a. \(\displaystyle 4.09×10^3m/s\);
b. \(\displaystyle 7.83×10^3m;\)
c. \(\displaystyle 1.75×10^5m/s\), then, \(\displaystyle 1.83×10^2m\);
d. \(\displaystyle 4.27m\)
31. a. \(\displaystyle 1.8×10^7m/s\);
b. \(\displaystyle 6.8×10^6eV\);
c. \(\displaystyle 3.4×10^6V\)
33. a. left;
b. into the page;
c. up;
d. no force;
e. right;
f. down
35. a. into the page;
b. left;
c. out of the page
37. a. 2.50 N;
b. This means that the light-rail power lines must be attached in order not to be moved by the force caused by Earth’s magnetic field.
39. a. \(\displaystyle τ=NIAB\), so \(\displaystyle τ\) decreases by 5.00% if B decreases by 5.00%;
b. 5.26% increase
41. 10.0 A
43. \(\displaystyle A⋅m^2⋅T=A⋅m^2.\frac{N}{A⋅m}=N⋅m\)
45. \(\displaystyle 3.48×10^{−26}N⋅m\)
47. \(\displaystyle 0.666N⋅m\)
49. \(\displaystyle 5.8×10^{−7}V\)
51. \(\displaystyle 4.8×10^7C/kg\)
53. a. \(\displaystyle 4.4×10^{−8}s\);
b. 0.21 m
55. a. \(\displaystyle 1.92×10^{−12}J\);
b. 12 MeV;
c. 12 MV;
d. \(\displaystyle 5.2×10^{−8}s\);
e. \(\displaystyle 1.92×10^{−12}J\), 12 MeV, 12 V, \(\displaystyle 10.4×10^{−8}s\)
57. a. \(\displaystyle 2.50×10^{−}2m\);
b. Yes, this distance between their paths is clearly big enough to separate the U-235 from the U-238, since it is a distance of 2.5 cm.
Additional Problems
59. \(\displaystyle −7.2×10^{−15}N\hat{j}\)
61. \(\displaystyle 9.8×10^{−5}\hat{j}T\); the magnetic and gravitational forces must balance to maintain dynamic equilibrium
63. \(\displaystyle 1.13×10^{−3}T\)
65. \(\displaystyle 1.6\hat{i}−1.4\hat{j}−1.1\hat{k})×10^5V/m\)
67. a. circular motion in a north, down plane;
b. \(\displaystyle (1.61\hat{j}−0.58\hat{k})×10^{−14}N\)
69. The proton has more mass than the electron; therefore, its radius and period will be larger.
71. \(\displaystyle 1.3×10^{−25}kg\)
73. 1:0.707:1
75. 1/4
77. a. \(\displaystyle 2.3×10^{−4}m\);
b. \(\displaystyle 1.37×10^{−4}T\)
79. a. \(\displaystyle 30.0°\);
b. 4.80 N
81. a. 0.283 N;
b. 0.4 N;
c. 0 N;
d. 0 N
83. 0 N and 0.012 Nm
85. a. \(\displaystyle 0.31Am^2\);
b. 0.16 Nm
87. \(\displaystyle 0.024Am^2\)
89. a. \(\displaystyle 0.16Am^2\);
b. 0.016 Nm;
c. 0.028 J
91. (Proof)
93. \(\displaystyle 4.65×10^{−7}V\)
95. Since \(\displaystyle E=Blv\), where the width is twice the radius, \(\displaystyle I=2r,I=2r, I=nqAv_d\),\(\displaystyle v_d=\frac{I}{nqA}=\frac{I}{nqπr^2}\) so \(\displaystyle E=B×2r×\frac{I}{nqπr^2}=\frac{2IB}{nqπr}∝\frac{1}{r}∝\frac{1}{d}.\) The Hall voltage is inversely proportional to the diameter of the wire.
97. \(\displaystyle 6.92×10^7m/s\); 0.602 m
99. a. \(\displaystyle 2.4×10^{−19}C\);
b. not an integer multiple of e;
c. need to assume all charges have multiples of e, could be other forces not accounted for
101. a. B = 5 T;
b. very large magnet;
c. applying such a large voltage
Challenge Problems
103. \(\displaystyle R=(mvsinθ)/qB;p=(\frac{2πm}{eB})vcosθ\)
105. \(\displaystyle IaL^2/2\)
107. \(\displaystyle m=\frac{qB_0^2}{8V_{acc}}x^2\)
109. 0.01 N


5.3A: Sweat (Sudoriferous) Glands
Sweat glands, also known as sudoriferous glands, are distributed over most of the body surface.
LEARNING OBJECTIVE
Classify eccrine and apocrine sweat glands
Key Takeaways
Key Points
- Sweat glands are located deep within the skin and primarily regulate temperature.
- The two main types of sweat glands are eccrine sweat glands and apocrine sweat glands.
- Eccrine sweat glands are smaller sweat glands. They are coiled tubular glands that discharge their secretions directly onto the surface of the skin.
- Apocrine sweat glands are coiled tubular glands that discharge in the canals of hair follicles. The sweat produced may be acted upon by bacteria, causing a noticeable odor.
Key Terms
- eccrine gland : The major sweat glands of the human body, found in virtually all skin, produce a clear, odorless substance, consisting primarily of water and NaCl.
- apocrine sweat gland : The type of sweat gland that is least responsible for thermoregulation and most responsible for body odor.
Sweat glands, also called sudoriferous glands, are simple tubular glands found almost everywhere on our body. Each sweat gland is made up of two portions:
- A secretory section
- An excretory duct
The secretory portion is found in the dermis, the middle layer of the skin. Sometimes it’s also found in the hypodermis, the deepest layer of our skin.
The secretory portion of a sweat gland is a twisted and coiled tube that has an opening at its very top. It is in the coiled secretory portion of the sweat gland where the sweat is actually produced. The excretory duct moves from the secretion portion, through the dermis, and into the topmost layer of the skin, the epidermis, where it opens up at the surface of our skin.
Eccrine Glands
Human Skin: Cross sectional image of skin showing a sweat gland and a sebaceous gland.
The most numerous types of sweat glands in our skin, found almost everywhere on the body, are called eccrine glands. These are the true sweat glands in the sense of helping to regulate body temperature. In other words, sweating causes the loss of body heat and thus cools us down on a hot day or when performing strenuous exercise. This is because as the water in sweat evaporates, it takes body heat with it.
Apocrine Glands
The other kind of sweat glands are known as apocrine glands. The apocrine glands are found in places like the armpits, scrotum, anus, and labia majora. They are typically larger than eccrine glands and their ducts tend to open into hair follicles instead of hairless areas of skin.
These glands, unlike the eccrine glands, serve virtually no role in the regulation of body temperature. These are also the glands largely responsible for body smells, as their excretions are converted by skin bacteria into various chemicals we associated with body odor.
Unlike eccrine glands, the exact function of apocrine glands is unknown and debated. We do know they are activated during times of stress, pain, and sexual foreplay but for what reasons is yet to be made clear.


2.6: Exercises
EXERCISE 2.1. Which of the properties of reflexivity, symmetry, antisymmetry and transitivity apply to the relations given in Examples 2.1-2.4?
ExERCISE 2.2. Prove that the relation in Example \(2.6\) is a partial ordering.
EXERCISE 2.3. List every pair in the relation given in Example 2.10.
ExERCISE 2.4. Prove that the relation in Example \(2.17\) is an equivalence.
EXERCISE 2.5. Prove that congruence \(\bmod n\) is an equivalence relation on \(\mathbb{Z}\) .
EXERCISE 2.6. Prove that two integers are in the same congruence class \(\bmod n\) if and only if they have the same remainder when divided by \(n\) .
EXERCISE 2.7. Suppose \(R\) is a relation on \(X\) . What does it mean if \(R\) is both a partial order and an equivalence?
EXERCISE 2.8. Consider the relations on people "is a brother of", "is a sibling of", "is a parent of", "is married to", "is a descendant of". Which of the properties of reflexivity, symmetry, antisymmetry and transitivity do each of these relations have? EXERCISE 2.9. Let \(X=\{k \in \mathbb{N}: k \geq 2\}\) . Consider the following relations on \(X\) :
(i) \(j R_{1} k\) if and only if \(\operatorname{gcd}(j, k)>1(\operatorname{gcd}\) stands for greatest common divisor).
(ii) \(j R_{2} k\) if and only if \(j\) and \(k\) are coprime (i.e. \(\operatorname{gcd}(j, k)=1\) ).
(iii) \(j R_{3} k\) if and only if \(j \mid k\) .
(iv) \(j R_{4} k\) if and only if \[\{p: p \text { is prime and } p \mid j\}=\{q: q \text { is prime and } q \mid k\} .\] For each relation, say which of the properties of Reflexivity, Symmetry, Antisymmetry, Transitivity it has.
ExERCISE 2.10. For \(j, k\) in \(\mathbb{N}^{+}\) , define two relations \(R_{1}\) and \(R_{2}\) by \(j R_{1} k\) if \(j\) and \(k\) have a digit in common (but not necessarily in the same place) and \(j R_{2} k\) if \(j\) and \(k\) have a common digit in the same place (so, for example, \(108 R_{1} 82\) , but \((108,82) \notin R_{2}\) ).
(i) If \(j=\sum_{m=0}^{M} a_{m} 10^{m}\) and \(k=\sum_{n=0}^{N} b_{n} 10^{n}\) , with \(a_{M} \neq 0\) and \(b_{N} \neq 0\) , how can one mathematically define \(R_{1}\) and \(R_{2}\) in terms of the coefficients \(a_{m}\) and \(b_{n}\) ?
(ii) Which of the four properties of reflexivity, symmetry, antisymmetry and transitivity do \(R_{1}\) and \(R_{2}\) have?
EXERCISE 2.11. Let \(X=\{a, b\}\) . List all possible relations on \(X\) , and say which are reflexive, which are symmetric, which are antisymmetric, and which are transitive.
EXERCISE 2.12. How many relations are there on a set with 3 elements? How many of these are reflexive? How many are symmetric? How many are anti-symmetric?
EXERCISE 2.13. Repeat Exercise \(2.12\) for a set with \(N\) elements.
ExERCISE 2.14. The sum of two even integers is even, the sum of an even and an odd integer is odd, and the sum of two odd integers is even. What is the generalization of this statement to residue classes \(\bmod 3\) ? EXERCISE 2.15. What is the last digit of \(3^{5^{7}}\) ? Of \(7^{5^{3}}\) ? Of \(11^{10^{6}}\) ? Of \(8^{5^{4}}\) ?
ExERCISE 2.16. What is \(2^{1000000} \bmod 17\) ? What is \(17^{77} \bmod 14\) ?
EXERCISE 2.17. Show that a number’s residue \(\bmod 3\) is the same as the sum of its digits.
ExERCISE 2.18. Show that the assertion of Exercise \(2.17\) is not true \(\bmod n\) for any value of \(n\) except 3 and 9 .
EXERCISE 2.19. Prove that there are an infinite number of natural numbers that cannot be written as the sum of three squares. (Hint: Look at the possible residues mod 8).
EXERCISE 2.20. Let \(f: X \rightarrow Y\) and \(g: Y \rightarrow Z\) . What can you say about the relationship between \(X / f\) and \(X /(g \circ f)\) ?
ExERCISE 2.21. Let \(R\) be the relation on \(X=\mathbb{Z} \times \mathbb{N}^{+}\) defined in Example 2.17. Define an operation \(\star\) on \(X / R\) as follows: for \(x=(a, b)\) and \(y=(c, d)\) , \[[x] \star[y]=[(a d+b c, c d)] .\] Is \(\star\) well-defined?
EXERCISE 2.22. Let \(X\) be the set of functions from finite subsets of \(\mathbb{N}\) to \(\ulcorner 2\urcorner\) (that is \(f \in X\) iff there is a finite set \(D \subseteq \mathbb{N}\) such that \(f: D \rightarrow\ulcorner 2\urcorner\) ). Define a relation \(R\) on \(X\) as follows: if \(f, g \in X, f R g\) iff \(\operatorname{Dom}(g) \subseteq \operatorname{Dom}(f)\) and \(g=\left.f\right|_{\operatorname{Dom}(g)}\) . Is \(R\) a partial ordering? Is \(R\) an equivalence relation?
ExERCISE \(2.23\) . Let \(X\) be the set of all infinite binary sequences. Define a relation \(R\) on \(X\) as follows: For any \(f, g \in X, f R g\) iff \(f^{-1}(1) \subseteq\) \(g^{-1}(1)\) . Is \(R\) a partial ordering? Is \(R\) an equivalence relation?
EXERCISE 2.24. Let \(X=\{\ulcorner n\urcorner \mid n \in \mathbb{N}\}\) . Let \(R\) be a relation on \(X\) defined by \(x, y \in R\) iff \(x \subseteq y\) . Prove that \(R\) is a linear ordering. ExERCISE 2.25. Let \(X=\{f: \mathbb{R} \rightarrow \mathbb{R} \mid f\) is a surjection \(\}\) . Define a relation \(R\) on \(X\) by \(f R g\) iff \(f(0)=g(0)\) . Prove that \(R\) is an equivalence relation. Let \(F: X \rightarrow \mathbb{R}\) be defined by \(F(f)=f(0)\) . Show that the level sets of \(F\) are the equivalence classes of \(X / R\) . That is show that \[X / R=X / F .\] EXERCISE 2.26. Let \(f: X \rightarrow Y\) . Show that \(X / f\) is composed of singletons (sets with exactly one element) iff \(f\) is an injection.


9.3: Design to Enable Human Capabilities
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For the past 50 years, two main trends have been observed in general education:
- the socio-cultural focus; and
- the integration of technology in educational practice.
However, still in its infancy, e-learning has yet to construct models of design to reach socio-cultural learning targets. There is as yet to employ consideration of the learner and user (Wallace, 1999; Smulders, 2002). Poor interfaces do not support e-learners efficiently and effectively, even though the existing commercial and open source learning management systems (LMS) provide several applications and tools. Most learning management systems are based on a constructivist model, and not on an e-learning community and reflective model of supporting distance education (Rumble, 2001). There are, therefore, no multiple perspectives of e-learning’s theoretical framework. Evaluators are still not supported by coherent, interdisciplinary evaluation frameworks and tools. This results in inadequate understanding and lack of descriptions of quality factors. To Silius and Tervakari (2003), one evaluator, whether s/he is a teacher or a systems’ designer or a quality planner, can hardly be an expert in all aspects. Collaboration between the stakeholders is the first step towards the adoption of a more social model for e-learning.
The Social Dimension of Learning in Design
Computer-supported collaborative learning (CSCL): The social aspects of learning with the aid of computer networks first appeared in CSCL. This followed the computer-supported collaborative work (CSCW) that utilised ethnography (Garfinkel, 1967) in systems design. Ethnography provides descriptions of qualitative and quantitative data about human social phenomena based on fieldwork, and was used to search for descriptions that could provide abstract specifications for systems design, i.e., finding ways to communicate to the designers what users want. Thus, the research of Hughes and colleagues was based on socio-technical design (STD) (Mumford, 1983; Fan, 2006) to inform the designers of system requirements. The STD mission was to assist system designers to maximize human gains while achieving business and technical excellence (Mumford, 1983). It recognises the interaction of technology and people, and produces work systems that are both technically efficient and have social characteristics. CSCL is linked to STD via CSCW (Hughes et al., 1997) and is anchored in the notion that, the system cannot be accurately understood as each property depends on the other.
Computer-supported collaborative learning (CSCL) was based on theories that emphasized the social dimension of learning, such as distributed cognition (Hutchins, 1995; Salomon, 1993); activity theory (Engestrom, 1987; Kuutti, 1996); situated learning (Resnick, Levine & Teasley, 1991); Greeno, Smith & Moore, 1993); collaborative learning (Crook, 1994); and legitimate peripheral participation in communities of practice (Lave & Wenger, 1991; Wenger, 1998; Wenger et al., 2002). Collaborative computer-supported collaborative learning has contributed significantly to the socio-cultural field.
Network-supported collaborative learning (NSCL): NSCL has emerged as a similar educational paradigm. It includes cognitive sciences, sociology, and computer engineering. See Banks, Goodyear, Hodgson & McConnell, 2004; Steeples and Jones, 2002. This interdisciplinary approach has also introduced the role of learning technologist (Conole & Oliver, 2002; Conole, 2004). However, owing to inherent difficulties in performing evaluation in general, as well as evaluation in its own field, very few systematic and complete studies have been reported in NSCL literature (Retalis et al., 2006).
Research in computer-supported collaborative learning and network-supported collaborative learning have found common ground between disciplines, and is now focused on learners working collaboratively. There is still the need, however, for the teacher and the technologist to acknowledge the individual e-learner’s requirements. In fact, the learner behaves as a learner, a user, and a customer. Even though learning technologists have aimed to fill this gap, the result is still techno-centric design and poor usability (Diaz, 2002; Notess, 2001). The problem remains. There is need for learning management systems to provide an integrated platform for collaborative learning in communities of practice (CoP, Lave & Wenger, 1991). Delivery of the learning product, supporting management, engagement, and tracking of information and activities should facilitate e-learning communities. The Web 2.0 philosophy and tools are currently in favour of such initiatives, but the systems are still in the first stage of development supporting information provision that community knowledge building.
Socio-technical design requires social software qualities of sympathy, trust, and integrity (Mumford, 1983). In e-learning this has been referred to as affective learning (AL). Affective learning properties link the individual with the community. Such properties include the emotions, intentions, attitudes, interests, attention, awareness, trust, motivation. or empathy enable communication, consultation, and participation (Zaharias, 2004). For example, Grosz and Sidner (1986) suggest that the discourse structure is intimately connected to intention; for instance intentional information in discourse structure creates adaptation of a conversational channel (Woodruff & Aoki, 2004). Empathy is another example, which is considered essential for participation in online communities (Preece, 1999; Preece & Ghozati, 2000; Lambropoulos, 2005).
Affective learning in design: A learner-centred approach to e-learning quality relies not only on cognitive but also on emotional and affective learners’ engagement (Zaharias, 2004). Such a learner-centred approach acknowledges the importance of context, and views learning as a social and collaborative process. In the learner-centred paradigm, learners are the focal point— the centre of the learning process. They should take responsibility for their own learning, reflect, and make sense of their experiences. Interconnections between the dual persona of the learner as a user, as well as the inclusion of affective learning factors are the links between the individual and the learning community in the e-learning world. The development of brain research (LeDoux, 1998) and cognitive neuroscience allowed Rizzolati and Arbib (1998) to discover the areas where the mirror neurons are located, interacting in both hemispheres (Broca are 44 and PE/PC). Such neurons are responsible for representing the existence of other people in the brain. This discovery resulted in the scientific identification of empathy, widespread in online communities (Preece & Ghozati, 2000).
According to Zaharias (2004), such affective networks justify the why in learning as humans pursue goals, develop preferences, build confidence, persist in the face of difficulty, establish priorities, and care about learning. And yet, affective networks are not considered important in educational technology. It is generally difficult to engineer empathy, but with the advantage the affective learning factors provide, learning theories for the individual can co-exist with socio-cultural learning. The learning activity is the outcome, as Zaharias stressed. Learner-centred frameworks and principles should require learners to be active participants in every quality assessment process. In order to achieve this, Zaharias provided a set of quality principles and their implications for e-learning instructional design quality. His seven quality principles associated with specific implications for e-learning design quality are:
- individual differences relevant to learning styles and preferences
- information overload
- contextual learning
- social learning
- active learning
- reflective learning
- emotional engagement focusing on motivation.
Zaharias’ quality principles echo the need for a systems’ design model that can support the formation of e-learning communities for the benefit of the individual and the community. Currently, there is still need of support of collaborative activities and active participation integrated applications. The first generation of learning management systems (LMS) was focused on information provision and management rather than learning. The new generation of LMSs following Web 2.0 philosophy needs to support the learners in their collaborative activities.
Enabling Human Capabilities: Design for Learners as Users and Users as Learners
Design for learners-users-customers refers to Shackel’s definition of user-centred design (1991). He suggested that designers need to enable human capabilities. To achieve this, the individual needs to meet the purpose of systems design without any additional cognitive and physical struggle to use it. The International Organization for Standardization (ISO) defined usability as a measure of quality of user experience when interacting with a system, in terms of effectiveness, efficiency, and satisfaction (ISO FDIS 9241-11, 1997). Faulkner (2000) suggested that users who do not have to learn to use the system, as the system is already easily used, are freed from the restrictions of their own ability to learn. Initial adaptation of the right attitude is of primary importance (Faulkner, 2000, p. 78). This implies that ensuring usability enables the ability to learn.
Instructional design (ID) is a process of resolving instructional problems through systematic analysis of learning conditions. ID starts with the initialization and project planning phase (how the instructional design is carried out); the design and development phase (appropriate strategies and approaches in targeted contexts); a QA phase is focused on evaluation and deployment. The general observation of Bichelmeyer and colleagues (2004) is that the process for most instructional designers is the same: analyze, design, develop, implement, and evaluate (ADDIE). However, Schwier and colleagues (2006) complain that systematic models of ID do not reflect actual practice, are cumbersome, ineffective, inefficient, and costly to implement. This is due to several reasons including unfamiliarity of stakeholders with ID, division between ‘academic’ and ‘corporate’ approaches, and unawareness for the need of quality standards. He has reason. Whereas learner-centred design (LCD) is focused on making users more effective e-learners, user-centred design (UCD) is focused on making e-learners effective users in order to free them from cognitive and physical constraints, making the system easy to use. These two activities as Wallace (1999) claimed should be networked on shared social interfaces for users-as-learners and learners-as-users. This is e-learner-centred design.
To date, the focus has been on the technological (techno-centric interfaces) and not on the social aspects of learning. Thus, there are still issues for useful and usable design in support of e-learning (CHI SIG, 2001). Researchers are still seeking a design to solve such quality problems (Muir et al., 2003; Silius et al., 2003b; Zaharias, 2005). A socio-technical approach for a learner-centred design (LCD) was adopted in turn by Soloway et al., 1994; by Norman & Spohrer, 1996 and Wallace et al., 1998. Their work aimed to bridge the gap between learners as users. At the time, Norman and Spohrer suggested that LCD has three dimensions:
- engagement
- effectiveness by measuring the quality
- viability of interventions.
In support of the third dimension, they observed that projects “won’t scale to real curriculum needs or large numbers of students, or diverse content areas, or to everyday teachers and students rather than handpicked ones”. They also emphasized the importance of active participation, evaluation, and implementation of design interventions in real-life settings.
Their example of a combined LCD framework has been developed by later researchers along different lines. Whereas Muir and colleagues (2003) worked on pedagogical usability for online courses for learning language, Daniel and colleagues (2005) worked on a variety of user-centred evaluation approaches to consider methods for determining whether a learning community exists, attempting to isolate and understand interactions among its constituent elements. Zaharias (2004) on the other hand developed a questionnaire-based usability evaluation technique that relies upon web usability and instructional design parameters, associating them with a motivation to learn. The latter is proposed as a new affective-oriented measure for e-learning usability.
It appears that combined frameworks are necessary to go out of the control room and controlled experimentation and adjust the interventions to stakeholders’ needs. In addition, measurement and evaluation is not towards control but to support successful designs and eliminate existing problems.
Every learning context is unique. Parker (2003) believes that there is an ideological congruence with the reduction of “citizens” to “taxpayers”, and as the focus moves to “value-added” activities, the terrain of the debate is being narrowed to shorter and shorter transactional terms. Their focus on institutional policy and teaching with learning styles based on all stakeholders’ targets is not a disadvantage and, in this chapter, it is worth considering a focus depending on active participation in collaborative learning. Understanding the controlling processes and improving them by evaluation and assessment will eliminate existing problems.


5.17: Reading- Social Responsibility Initiatives
The Business Case for Social Responsibility
Regardless of broader benefits, there is a strong business case for social responsibility. Public companies’ stock prices benefit from strong social responsibility initiatives. In 2013, more than $6.57 trillion were invested based on socially responsible investment strategies. [1]
For marketers, the desire for socially responsible products and companies is driven by consumers. Nearly 30 percent of consumers plan to increase the amount of goods and/or services they buy from socially responsible companies in the coming year. Twenty-five percent avoided buying products from an enterprise because they thought it wasn’t socially responsible. [2]
Social Responsibility Programs
In defining social responsibility programs and goals, companies are acknowledging a commitment to creating a better world. How do they determine where to focus these efforts and what are they trying to achieve? Generally, companies are expanding on unique market strengths that benefit society and trying to reduce the negative impact of their products on society. As with any other business strategy, an approach that is customized to the company and its market is likelier to have greater impact. For example, Coca-Cola’s emphasis on preventing childhood obesity acknowledges and addresses a risk that the company brings to its market. If Exxon Mobile launched a childhood obesity initiative, it wouldn’t have the same impact. The company’s oil and gas offerings don’t have a direct impact on childhood obesity, and thus it would raise questions about the energy company’s commitment to addressing issues much closer to home—i.e., the serious impact that Exxon Mobile products have on the environment.
Many companies are implementing a host of social responsibility strategies through sustainable product initiatives.
Creating Sustainable Products
A sustainable product is constantly environmental-friendly during its entire life. That is, from the moment the raw materials are extracted to the moment the final product is disposed of, there must be no permanent damage to the environment. [3]
A sustainable product focus may include:
- Use of organic raw materials
- Sustainably harvesting of raw materials
- Emphasizing human rights and labor conditions in sourcing decisions
- Use of renewable energy in the production process
- Ensuring that use of the product creates a positive impact on the community
- Creating product recycling and reuse options
- Improving the impact of the product’s use on human and environmental health
The intent of a sustainable product strategy is that the company is identifying the impact of its products on society at every phase of the product lifecycle, and minimizing the negative impacts. Sustainable product initiatives are so broad in scope that they often encompass all of the social responsibility initiatives. This broad scope also requires companies to be focused and realistic about what they can achieve, setting appropriate objectives that demonstrate progress and identify where more work is needed.
As the world’s largest retailer, Wal-Mart faces unique challenges in product sustainability. It must not only focus on its stores, but on the products provided and transported by a board network of suppliers. To address this, Wal-Mart has partnered with The Sustainability Consortium to create a sustainability index that can be used to set standards and measure progress across its value chain. The goals of the index are to:
- Improve the sustainability of the products customers love
- Integrate sustainability into the business of buying and selling merchandise
- Reduce cost, improve product quality and create a more resilient supply chain
- Strengthen customers’ trust in retailers and the brands we carry
The company cites progress in its work to date.
One great example of how we are delivering impact is through the progress we’ve made on our goal to eliminate 20 million metric tons (MMT) of greenhouse gas (GHG) emissions from the supply chain. Through our partnership with the Environmental Defense Fund and by leveraging the Index as a tool to gain buy-in and create accountability, we’ve:
- Eliminated 7.575 MMT of GHG by the end of 2013
- Implemented projects that are estimated to eliminate 18MMT of GHG emissions by the end of 2015 [4]
Clearly, Walmart has significant work ahead, but independent evaluations have been positive. Joel Makower of Green Biz reports that Walmart’s sustainability initiatives are having a real impact, both on its operations and those of the companies in its supply chain. He also notes that some of that progress is offset by the company’s rapid growth. [5]
- http://www.ussif.org/sribasics ↵
- http://www.forbes.com/sites/annefield/2013/04/05/consumers-like-social-responsibility-but-they-arent-sure-what-a-social-enterprise-is/ ↵
- Frank-Martin B. and Peattie, K. (2009). Sustainability Marketing: A Global Perspective. Wiley, United Kingdom. ↵
- corporate.walmart.com/article/sustainability-index ↵
- http://www.greenbiz.com/article/walmart-sustainability-10-assessment ↵
Contributors and Attributions
- Social Responsibility Initiatives. Provided by : Lumen Learning. License : CC BY: Attribution


10.4: A Brief Biography of Raymond Cattell
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Raymond Bernard Cattell was born on March 20, 1905, in the seaside town of Staffordshire, England. Cattell developed a great love for the sea, and his first book was actually about sailing. His father was a mechanical engineer who worked on projects such as innovations for WWI military equipment, the steam engine, and the new internal combustion engine. Cattell was an excellent student, and he earned a scholarship to attend London University. He majored in chemistry, and he received his bachelor’s degree in 1924, with first class honors.
The years following World War I were a time of great change in Europe, and Cattell decided that studying psychology would provide him with the opportunity to address the political and economic issues facing society. He entered University College in London, where he worked on his Ph.D. with Charles Spearman, the renowned statistician and expert on intelligence testing (a student of Wilhelm Wundt, and advisor to David Wechsler as well). During his studies, he was involved in the development of factor analysis, a new statistical method that was to have a profound effect on the development of psychological tests (including the MMPI). He completed his Ph.D. in 1929, after which he both worked and continued his education. He spent six years as the director of the City Psychological Clinic, a child guidance center in Leicester, earned a master’s degree in education, and a doctorate of science degree.
In 1937, he came to America to work with E. L. Thorndike at Columbia University, where he continued his work on theories of intelligence. In 1939, he moved to Clark University, where his research interests turned to developing objective measures of personality. In part, this work led to his theory on fluid vs. crystallized intelligence. Then, in 1941, at the invitation of Allport, Cattell joined the faculty at Harvard University. While at Harvard, he was influenced by Allport and Henry Murray, and Cattell became even more strongly interested in the study of personality. It was in this stimulating environment that be began to consider applying factor analysis to the study of personality.
In 1945, Cattell accepted a research professorship at the University of Illinois, where he remained for nearly 30 years. The University of Illinois soon became the site of the first electronic computer, providing Cattell with the technology necessary to conduct large-scale factor-analytic studies on personality (factor analysis is a math intensive statistical technique, even relative to other statistical techniques). He established the Laboratory of Personality Assessment and Group Behavior, where he and his colleagues were highly productive and produced a number of influential books advancing psychological science, including Description and Measurement of Personality (Cattell, 1946), An Introduction to Personality Study (Cattell, 1950a), Personality: A Systemic Theoretical and Factual Study (Cattell, 1950b ), Factor Analysis (Cattell, 1952), and Personality and Motivation Structure and Measurement (Cattell, 1957). In these books, Cattell gathered together extensive data from a methodologically sophisticated program of research on the development and organization of personality. In 1960, he called for an international meeting of researchers in the scientific study of personality, which resulted in the foundation of the Society of Multivariate Experimental Psychology, and in 1966 he co-wrote and edited the influential Handbook of Multivariate Experimental Psychology (Cattell, 1966).
After retiring in 1973, Cattell continued his research in Colorado. In 1978, he moved to Hawaii, where he taught at the University of Hawaii and the Hawaii School of Professional Psychology (which later became the American School of Professional Psychology). During his career, Cattell received many honors, including the Wenner-Gren Prize from the New York Academy of Sciences, and in 1972 the Society of Multivariate Experimental Psychology established the Cattell Award for young psychologists. In 1997, he was chosen to receive a Gold Medal Award for Life Achievement (the same honor received by both Gordon and Floyd Allport). However, the announcement resulted in objections that Cattel should not be honored, because he had used his psychological theories to support eugenics. Essentially, he was accused of using his research to support racism, and, therefore, he was a racist. In an open letter to the American Psychological Association, Cattell claimed that his views had been misinterpreted, and that he was being held accountable for statements made as a young man in the 1930s. However, he continued to publish these controversial ideas in the 1970s and 1980s. Regardless, Cattell asked that his name be withdrawn from consideration. Less than two months after writing the letter, Cattell died at his home in Honolulu on February 2, 1998 (Cattell & Horn, 2007; Gale Reference Team, 2004).
Placing Cattell in Context: Statistical Analysis of Trait Dimensions
Raymond Cattell stands alongside Allport as one the two principal founders of the trait approach to understanding personality. As his unique contribution, Cattell brought a level of precision to the scientific and statistical analysis of personality factors that was not available beforehand. Indeed, Cattell helped to develop the factor analysis method that revolutionized objective psychological testing. His 16-PF test was the forerunner of the research that led to today’s highly regarded conception of the Big Five personality traits.
In addition, although he is not generally known for it, Cattell was one of the few early personality theorists who considered the continuation of personality development throughout the lifespan. His publication of these ideas coincides with Erik Erikson’s publication of his first major book, so Cattell was not simply echoing the work of someone who came before him, but rather had developed this interest on his own.
Unfortunately, Cattell also provided the basis for one of the most controversial topics in psychology today. Specifically, he advocated directing the efforts and support of society toward those already advantaged within it. In contrast, the discipline of psychology, as a social science, is held by the vast majority of its members to expectations of ethics and morality that emphasize improving the good of all people. Thus, most psychologists would agree that our discipline, as well as our society, should focus most of its support on those who need it most, even if that approach does not stand up well to a cost-benefit analysis. After all, how does one apply the concept of costs and benefits to the value of a human being?


5.12: Active Transport - Secondary Active Transport
- Differentiate between primary and secondary active transport
Secondary Active Transport (Co-transport)
Unlike in primary active transport, in secondary active transport, ATP is not directly coupled to the molecule of interest. Instead, another molecule is moved up its concentration gradient, which generates an electrochemical gradient. The molecule of interest is then transported down the electrochemical gradient. While this process still consumes ATP to generate that gradient, the energy is not directly used to move the molecule across the membrane, hence it is known as secondary active transport. Both antiporters and symporters are used in secondary active transport. Co-transporters can be classified as symporters and antiporters depending on whether the substances move in the same or opposite directions across the cell membrane.
Secondary active transport brings sodium ions, and possibly other compounds, into the cell. As sodium ion concentrations build outside the plasma membrane because of the action of the primary active transport process, an electrochemical gradient is created. If a channel protein exists and is open, the sodium ions will be pulled through the membrane. This movement is used to transport other substances that can attach themselves to the transport protein through the membrane. Many amino acids, as well as glucose, enter a cell this way. This secondary process is also used to store high-energy hydrogen ions in the mitochondria of plant and animal cells for the production of ATP. The potential energy that accumulates in the stored hydrogen ions is translated into kinetic energy as the ions surge through the channel protein ATP synthase, and that energy is used to convert ADP into ATP.
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- active transport. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/active%20transport . License : CC BY-SA: Attribution-ShareAlike
- electrochemical gradient. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/electro...cal%20gradient . License : CC BY-SA: Attribution-ShareAlike
- adenosine triphosphate. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/adenosine%20triphosphate . License : CC BY-SA: Attribution-ShareAlike
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- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//biology/de...ctrogenic-pump . License : CC BY-SA: Attribution-ShareAlike
- Na -K ATPase. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Na%20-K%20%20ATPase . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Active Transport. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44418/latest...e_05_03_02.jpg . License : CC BY: Attribution
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- OpenStax College, Biology. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44418/latest...ol11448/latest . License : CC BY: Attribution
- Structural Biochemistry/Membrane Proteins. Provided by : Wikibooks. Located at : en.wikibooks.org/wiki/Structu...tive_Transport . License : CC BY-SA: Attribution-ShareAlike
- secondary active transport. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/seconda...ve%20transport . License : CC BY-SA: Attribution-ShareAlike
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Key Points
- While secondary active transport consumes ATP to generate the gradient down which a molecule is moved, the energy is not directly used to move the molecule across the membrane.
- Both antiporters and symporters are used in secondary active transport.
- Secondary active transport brings sodium ions into the cell, and as sodium ion concentrations build outside the plasma membrane, an electrochemical gradient is created.
- If a channel protein is open via primary active transport, the ions will be pulled through the membrane along with other substances that can attach themselves to the transport protein through the membrane.
- Secondary active transport is used to store high-energy hydrogen ions in the mitochondria of plant and animal cells for the production of ATP.
- The potential energy in the hydrogen ions is translated into kinetic energy as the ions surge through the channel protein ATP synthase, and that energy is used to convert ADP into ATP.
Key Terms
- secondary active transport : A method of transport in which the electrochemical potential difference created by pumping ions out of the cell is used to transport molecules across a membrane.


4.4: Chemical Nomenclature
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Learning Objectives
By the end of this section, you will be able to:
- Derive names for common types of inorganic compounds using a systematic approach
Nomenclature , a collection of rules for naming things, is important in science and in many other situations. This module describes an approach that is used to name simple ionic and molecular compounds, such as NaCl, CaCO 3 , and N 2 O 4 . The simplest of these are binary compounds , those containing only two elements, but we will also consider how to name ionic compounds containing polyatomic ions, and one specific, very important class of compounds known as acids (subsequent chapters in this text will focus on these compounds in great detail). We will limit our attention here to inorganic compounds, compounds that are composed principally of elements other than carbon, and will follow the nomenclature guidelines proposed by IUPAC. The rules for organic compounds, in which carbon is the principle element, will be treated in a later chapter on organic chemistry.
Ionic Compounds
To name an inorganic compound, we need to consider the answers to several questions. First, is the compound ionic or molecular? If the compound is ionic, does the metal form ions of only one type (fixed charge) or more than one type (variable charge)? Are the ions monatomic or polyatomic? If the compound is molecular, does it contain hydrogen? If so, does it also contain oxygen? From the answers we derive, we place the compound in an appropriate category and then name it accordingly.
Compounds Containing Only Monatomic Ions
The name of a binary compound containing monatomic ions consists of the name of the cation (the name of the metal) followed by the name of the anion (the name of the nonmetallic element with its ending replaced by the suffix – ide ). Some examples are given in Table \(\PageIndex{1}\).
| NaCl, sodium chloride | Na 2 O, sodium oxide |
| KBr, potassium bromide | CdS, cadmium sulfide |
| CaI 2 , calcium iodide | Mg 3 N 2 , magnesium nitride |
| CsF, cesium fluoride | Ca 3 P 2 , calcium phosphide |
| LiCl, lithium chloride | Al 4 C 3 , aluminum carbide |
Compounds Containing Polyatomic Ions
Compounds containing polyatomic ions are named similarly to those containing only monatomic ions, i.e. by naming first the cation and then the anion. Examples are shown in Table \(\PageIndex{2}\).
| KC 2 H 3 O 2 , potassium acetate | NH 4 Cl, ammonium chloride |
| NaHCO 3 , sodium bicarbonate | CaSO 4 , calcium sulfate |
| Al 2 (CO 3 ) 3 , aluminum carbonate | Mg 3 (PO 4 ) 2 , magnesium phosphate |
Chemistry in Everyday Life: Ionic Compounds in Your Cabinet
Every day you encounter and use a large number of ionic compounds. Some of these compounds, where they are found, and what they are used for are listed in Table \(\PageIndex{3}\). Look at the label or ingredients list on the various products that you use during the next few days, and see if you run into any of those in this table, or find other ionic compounds that you could now name or write as a formula.
| Ionic Compound | Use |
|---|---|
| NaCl, sodium chloride | ordinary table salt |
| KI, potassium iodide | added to “iodized” salt for thyroid health |
| NaF, sodium fluoride | ingredient in toothpaste |
| NaHCO 3 , sodium bicarbonate | baking soda; used in cooking (and as antacid) |
| Na 2 CO 3 , sodium carbonate | washing soda; used in cleaning agents |
| NaOCl, sodium hypochlorite | active ingredient in household bleach |
| CaCO 3 calcium carbonate | ingredient in antacids |
| Mg(OH) 2 , magnesium hydroxide | ingredient in antacids |
| Al(OH) 3 , aluminum hydroxide | ingredient in antacids |
| NaOH, sodium hydroxide | lye; used as drain cleaner |
| K 3 PO 4 , potassium phosphate | food additive (many purposes) |
| MgSO 4 , magnesium sulfate | added to purified water |
| Na 2 HPO 4 , sodium hydrogen phosphate | anti-caking agent; used in powdered products |
| Na 2 SO 3 , sodium sulfite | preservative |
Compounds Containing a Metal Ion with a Variable Charge
Most of the transition metals and some main group metals can form two or more cations with different charges. Compounds of these metals with nonmetals are named with the same method as compounds in the first category, except the charge of the metal ion is specified by a Roman numeral in parentheses after the name of the metal. The charge of the metal ion is determined from the formula of the compound and the charge of the anion. For example, consider binary ionic compounds of iron and chlorine. Iron typically exhibits a charge of either 2+ or 3+ (see Figure 2.29), and the two corresponding compound formulas are FeCl 2 and FeCl 3 . The simplest name, “iron chloride,” will, in this case, be ambiguous, as it does not distinguish between these two compounds. In cases like this, the charge of the metal ion is included as a Roman numeral in parentheses immediately following the metal name. These two compounds are then unambiguously named iron(II) chloride and iron(III) chloride, respectively. Other examples are provided in Table \(\PageIndex{4}\).
| Compound | Name |
|---|---|
| FeCl 2 | iron(II) chloride |
| FeCl 3 | iron(III) chloride |
| Hg 2 O | mercury(I) oxide |
| HgO | mercury(II) oxide |
| SnF 2 | tin(II) fluoride |
| SnF 4 | tin(IV) fluoride |
Out-of-date nomenclature used the suffixes – ic and – ous to designate metals with higher and lower charges, respectively: Iron(III) chloride, FeCl 3 , was previously called ferric chloride, and iron(II) chloride, FeCl 2 , was known as ferrous chloride. Though this naming convention has been largely abandoned by the scientific community, it remains in use by some segments of industry. For example, you may see the words stannous fluoride on a tube of toothpaste. This represents the formula SnF 2 , which is more properly named tin(II) fluoride. The other fluoride of tin is SnF 4 , which was previously called stannic fluoride but is now named tin(IV) fluoride.
Ionic Hydrates
Ionic compounds that contain water molecules as integral components of their crystals are called hydrates . The name for an ionic hydrate is derived by adding a term to the name for the anhydrous (meaning “not hydrated”) compound that indicates the number of water molecules associated with each formula unit of the compound. The added word begins with a Greek prefix denoting the number of water molecules (see Table \(\PageIndex{5}\)) and ends with “hydrate.” For example, the anhydrous compound copper(II) sulfate also exists as a hydrate containing five water molecules and named copper(II) sulfate pentahydrate. Washing soda is the common name for a hydrate of sodium carbonate containing 10 water molecules; the systematic name is sodium carbonate decahydrate.
Formulas for ionic hydrates are written by appending a vertically centered dot, a coefficient representing the number of water molecules, and the formula for water. The two examples mentioned in the previous paragraph are represented by the formulas
\[\text { copper(II) sulfate pentahydrate } \quad \ce{CuSO4 \cdot 5 H2O} \nonumber \]
\[\text { sodium carbonate decahydrate } \quad \ce{Na2CO3 \cdot 10 H2O} \nonumber \]
| Number | Prefix | Number | Prefix |
|---|---|---|---|
| 1 (sometimes omitted) | mono- | 6 | hexa- |
| 2 | di- | 7 | hepta- |
| 3 | tri- | 8 | octa- |
| 4 | tetra- | 9 | nona- |
| 5 | penta- | 10 | deca- |
Example \(\PageIndex{1}\): Naming Ionic Compounds
Name the following ionic compounds
- Fe 2 S 3
- CuSe
- GaN
- MgSO 4 ·7H 2 O
- Ti 2 (SO 4 ) 3
Solution
The anions in these compounds have a fixed negative charge (S 2− , Se 2 − , N 3− , and and the compounds must be neutral. Because the total number of positive charges in each compound must equal the total number of negative charges, the positive ions must be Fe 3 + , Cu 2 + , Ga 3 + , Mg 2 + , and Ti 3 + . These charges are used in the names of the metal ions:
- iron(III) sulfide
- copper(II) selenide
- gallium(III) nitride
- magnesium sulfate heptahydrate
- titanium(III) sulfate
Exercise \(\PageIndex{1}\)
Write the formulas of the following ionic compounds:
- chromium(III) phosphide
- mercury(II) sulfide
- manganese(II) phosphate
- copper(I) oxide
- iron(III) chloride dihydrate
- Answer
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(a) CrP; (b) HgS; (c) Mn 3 (PO 4 ) 2 ; (d) Cu 2 O; (e) FeCl 3 ·2H 2 O
Chemistry in Everyday Life: Erin Brockovich and Chromium Contamination
In the early 1990s, legal file clerk Erin Brockovich (Figure \(\PageIndex{1}\)) discovered a high rate of serious illnesses in the small town of Hinckley, California. Her investigation eventually linked the illnesses to groundwater contaminated by Cr(VI) used by Pacific Gas & Electric (PG&E) to fight corrosion in a nearby natural gas pipeline. As dramatized in the film Erin Brockovich (for which Julia Roberts won an Oscar), Erin and lawyer Edward Masry sued PG&E for contaminating the water near Hinckley in 1993. The settlement they won in 1996—$333 million—was the largest amount ever awarded for a direct-action lawsuit in the US at that time.
Chromium compounds are widely used in industry, such as for chrome plating, in dye-making, as preservatives, and to prevent corrosion in cooling tower water, as occurred near Hinckley. In the environment, chromium exists primarily in either the Cr(III) or Cr(VI) forms. Cr(III), an ingredient of many vitamin and nutritional supplements, forms compounds that are not very soluble in water, and it has low toxicity. But Cr(VI) is much more toxic and forms compounds that are reasonably soluble in water. Exposure to small amounts of Cr(VI) can lead to damage of the respiratory, gastrointestinal, and immune systems, as well as the kidneys, liver, blood, and skin.
Despite cleanup efforts, Cr(VI) groundwater contamination remains a problem in Hinckley and other locations across the globe. A 2010 study by the Environmental Working Group found that of 35 US cities tested, 31 had higher levels of Cr(VI) in their tap water than the public health goal of 0.02 parts per billion set by the California Environmental Protection Agency.
Molecular (Covalent) Compounds
The bonding characteristics of inorganic molecular compounds are different from ionic compounds, and they are named using a different system as well. The charges of cations and anions dictate their ratios in ionic compounds, so specifying the names of the ions provides sufficient information to determine chemical formulas. However, because covalent bonding allows for significant variation in the combination ratios of the atoms in a molecule, the names for molecular compounds must explicitly identify these ratios.
Compounds Composed of Two Elements
When two nonmetallic elements form a molecular compound, several combination ratios are often possible. For example, carbon and oxygen can form the compounds CO and CO 2 . Since these are different substances with different properties, they cannot both have the same name (they cannot both be called carbon oxide). To deal with this situation, we use a naming method that is somewhat similar to that used for ionic compounds, but with added prefixes to specify the numbers of atoms of each element. The name of the more metallic element (the one farther to the left and/or bottom of the periodic table) is first, followed by the name of the more nonmetallic element (the one farther to the right and/or top) with its ending changed to the suffix – ide . The numbers of atoms of each element are designated by the Greek prefixes shown in Table \(\PageIndex{5}\).
When only one atom of the first element is present, the prefix mono - is usually deleted from that part. Thus, CO is named carbon monoxide, and CO 2 is called carbon dioxide. When two vowels are adjacent, the a in the Greek prefix is usually dropped. Some other examples are shown in Table \(\PageIndex{6}\).
| Compound | Name | Compound | Name |
|---|---|---|---|
| SO 2 | sulfur dioxide | BCl 3 | boron trichloride |
| SO 3 | sulfur trioxide | SF 6 | sulfur hexafluoride |
| NO 2 | nitrogen dioxide | PF 5 | phosphorus pentafluoride |
| N 2 O 4 | dinitrogen tetroxide | P 4 O 10 | tetraphosphorus decaoxide |
| N 2 O 5 | dinitrogen pentoxide | IF 7 | iodine heptafluoride |
There are a few common names that you will encounter as you continue your study of chemistry. For example, although NO is often called nitric oxide, its proper name is nitrogen monoxide. Similarly, N 2 O is known as nitrous oxide even though our rules would specify the name dinitrogen monoxide. (And H 2 O is usually called water, not dihydrogen monoxide.) You should commit to memory the common names of compounds as you encounter them.
Example \(\PageIndex{2}\): Naming Covalent Compounds
Name the following covalent compounds:
- SF 6
- N 2 O 3
- Cl 2 O 7
- P 4 O 6
Solution
Because these compounds consist solely of nonmetals, we use prefixes to designate the number of atoms of each element:
- sulfur hexafluoride
- dinitrogen trioxide
- dichlorine heptoxide
- tetraphosphorus hexoxide
Exercise \(\PageIndex{2}\)
Write the formulas for the following compounds:
- phosphorus pentachloride
- dinitrogen monoxide
- iodine heptafluoride
- carbon tetrachloride
- Answer
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(a) PCl 5 ; (b) N 2 O; (c) IF 7 ; (d) CCl 4
Link to Learning
The following website provides practice with naming chemical compounds and writing chemical formulas. You can choose binary, polyatomic, and variable charge ionic compounds, as well as molecular compounds.
Binary Acids
Some compounds containing hydrogen are members of an important class of substances known as acids . The chemistry of these compounds is explored in more detail in later chapters of this text, but for now, it will suffice to note that many acids release hydrogen ions, H + , when dissolved in water. To denote this distinct chemical property, a mixture of water with an acid is given a name derived from the compound’s name. If the compound is a binary acid (comprised of hydrogen and one other nonmetallic element):
- The word “hydrogen” is changed to the prefix hydro-
- The other nonmetallic element name is modified by adding the suffix - ic
- The word “acid” is added as a second word
For example, when the gas HCl (hydrogen chloride) is dissolved in water, the solution is called hydrochloric acid . Several other examples of this nomenclature are shown in Table \(\PageIndex{7}\).
| Name of Gas | Name of Acid |
|---|---|
| HF( g ), hydrogen fluoride | HF( aq ), hydrofluoric acid |
| HCl( g ), hydrogen chloride | HCl( aq ), hydrochloric acid |
| HBr( g ), hydrogen bromide | HBr( aq ), hydrobromic acid |
| HI( g ), hydrogen iodide | HI( aq ), hydroiodic acid |
| H 2 S( g ), hydrogen sulfide | H 2 S( aq ), hydrosulfuric acid |
Oxyacids
Many compounds containing three or more elements (such as organic compounds or coordination compounds) are subject to specialized nomenclature rules that you will learn later. However, we will briefly discuss the important compounds known as oxyacids , compounds that contain hydrogen, oxygen, and at least one other element, and are bonded in such a way as to impart acidic properties to the compound (you will learn the details of this in a later chapter). Typical oxyacids consist of hydrogen combined with a polyatomic, oxygen-containing ion. To name oxyacids:
- Omit “hydrogen”
- Start with the root name of the anion
- Replace – ate with – ic , or – ite with – ous
- Add “acid”
For example, consider H 2 CO 3 (which you might be tempted to call “hydrogen carbonate”). To name this correctly, “hydrogen” is omitted; the – ate of carbonate is replace with – ic ; and acid is added—so its name is carbonic acid. Other examples are given in Table \(\PageIndex{8}\). There are some exceptions to the general naming method (e.g., H 2 SO 4 is called sulfuric acid, not sulfic acid, and H 2 SO 3 is sulfurous, not sulfous, acid).
| Formula | Anion Name | Acid Name |
|---|---|---|
| HC 2 H 3 O 2 | acetate | acetic acid |
| HNO 3 | nitrate | nitric acid |
| HNO 2 | nitrite | nitrous acid |
| HClO 4 | perchlorate | perchloric acid |
| H 2 CO 3 | carbonate | carbonic acid |
| H 2 SO 4 | sulfate | sulfuric acid |
| H 2 SO 3 | sulfite | sulfurous acid |
| H 3 PO 4 | phosphate | phosphoric acid |


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2.6.E: Earthlike Planets - Venus and Mars (Exercises)
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Last updated
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Save as PDF
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For Further Exploration
Articles
Venus
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Dorminey, B. “Cool Science on a Hot World.”
Astronomy
(February 2006): 46. Five-page overview of Venus and the Venus Express mission plans.
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Kargel, J. “Rivers of Venus.”
Sky & Telescope
(August 1997): 32. On lava channels.
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Robertson, D. “Parched Planet.”
Sky & Telescope
(April 2008): 26. Overview of our understanding of the planet.
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Robinson, C. “Magellan Reveals Venus.”
Astronomy
(February 1995): 32.
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Stofan, E. “The New Face of Venus.”
Sky & Telescope
(August 1993): 22.
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Zimmerman, R. “Taking Venus by Storm.”
Astronomy
(October 2008): 66. On results from the Venus Express mission.
Mars
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Albee, A. “The Unearthly Landscapes of Mars.”
Scientific American
(June 2003): 44. Results from the Mars Global Surveyor and Mars Odyssey missions and an overview.
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Bell, J. “A Fresh Look at Mars.”
Astronomy
(August 2015): 28. Nice summary of recent spacecraft results and how they are revising our understanding of Mars.
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Bell, J. “Uncovering Mars’ Secret Past.”
Sky & Telescope
(July 2009): 22. How rovers and orbiters are helping us to understand Mars history and the role of water.
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Bell, J. “The Red Planet’s Watery Past.”
Scientific American
(December 2006): 62. Rovers are furnishing proof that ancient Mars was wet.
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Burnham, R. “Red Planet Rendezvous.”
Astronomy
(May 2006): 68. About Mariner Valley and a flyover film constructed from many still images.
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Christensen, P. “The Many Faces of Mars.”
Scientific American
(July 2005): 32. Results from the Rover mission; evidence that Mars was once wet in places.
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Lakdawalla, E. “The History of Water on Mars.”
Sky & Telescope
(September 2013): 16. Clear review of our current understanding of the role of water on Mars in different epochs.
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Malin, M. “Visions of Mars.”
Sky & Telescope
(April 1999): 42. A geological tour of the red planet, with new Mars Global Surveyor images.
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McEwen, A. “Mars in Motion.”
Scientific American
(May 2013): 58. On gullies and other surface changes.
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McKay, C. & Garcia, V. “How to Search for Life on Mars.”
Scientific American
(June 2014): 44. Experiments future probes could perform.
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Naeye, R. “Europe’s Eye on Mars.”
Sky & Telescope
(December 2005): 30. On the Mars Express mission and the remarkable close-up images it is sending.
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Talcott, R. “Seeking Ground Truth on Mars.”
Astronomy
(October 2009): 34. How rovers and orbiters are helping scientists understand the red planet’s surface.
Collaborative Group Activities
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Your group has been asked by high NASA officials to start planning the first human colony on Mars. Begin by making a list of what sorts of things humans would need to bring along to be able to survive for years on the surface of the red planet.
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As a publicity stunt, the mayor of Venus, Texas (there really is such a town), proposes that NASA fund a mission to Venus with humans on board. Clearly, the good mayor neglected to take an astronomy course in college. Have your group assemble a list of as many reasons as possible why it is unlikely that humans will soon land on the surface of Venus.
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Even if humans would have trouble surviving on the surface of Venus, this does not mean we could not learn a lot more about our veiled sister planet. Have your group brainstorm a series of missions (pretend cost is no object) that would provide us with more detailed information about Venus’ atmosphere, surface, and interior.
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Sometime late in the twenty-first century, when travel to Mars has become somewhat routine, a very wealthy couple asks you to plan a honeymoon tour of Mars that includes the most spectacular sights on the red planet. Constitute your group as the Percival Lowell Memorial Tourist Agency, and come up with a list of not-to-be missed tourist stops on Mars.
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In the popular book and film, called
The Martian
, the drama really begins when our hero is knocked over and loses consciousness as he is half buried by an intense wind storm on Mars. Given what you have learned about Mars’ atmosphere in this chapter, have your group discuss how realistic that scenario is. (By the way, the author of the book has himself genially acknowledged in interviews and talks that this is a reasonable question to ask.)
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Astronomers have been puzzled and annoyed about the extensive media publicity that was given the small group of “true believers” who claimed the “Face on Mars” was not a natural formation (see the Astronomy and Pseudoscience: The “Face on Mars” feature box in Section 10.5). Have your group make a list of the reasons many of the media were so enchanted by this story. What do you think astronomers could or should do to get the skeptical, scientific perspective about such issues before the public?
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Your group is a special committee of scientists set up by the United Nations to specify how any Mars samples should be returned to Earth so that possible martian microbes do not harm Earth life. What precautions would you recommend, starting at Mars and going all the way to the labs that analyze the martian samples back on Earth?
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Have your group brainstorm about Mars in popular culture. How many movies, songs or other music, and products can you think of connected with Mars? What are some reasons that Mars would be a popular theme for filmmakers, songwriters, and product designers?
Review Questions
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List several ways that Venus, Earth, and Mars are similar, and several ways they are different.
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Compare the current atmospheres of Earth, Venus, and Mars in terms of composition, thickness (and pressure at the surface), and the greenhouse effect
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How might Venus’ atmosphere have evolved to its present state through a runaway greenhouse effect?
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Describe the current atmosphere on Mars. What evidence suggests that it must have been different in the past?
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Explain the runaway refrigerator effect and the role it may have played in the evolution of Mars.
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What evidence do we have that there was running (liquid) water on Mars in the past? What evidence is there for water coming out of the ground even today?
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What evidence is there that Venus was volcanically active about 300–600 million years ago?
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Why is Mars red?
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What is the composition of clouds on Mars?
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What is the composition of the polar caps on Mars?
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Describe two anomalous features of the rotation of Venus and what might account for them.
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How was the
Mars Odyssey
spacecraft able to detect water on Mars without landing on it?
Thought Questions
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What are the advantages of using radar imaging rather than ordinary cameras to study the topography of Venus? What are the relative advantages of these two approaches to mapping Earth or Mars?
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Venus and Earth are nearly the same size and distance from the Sun. What are the main differences in the geology of the two planets? What might be some of the reasons for these differences?
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Why is there so much more carbon dioxide in the atmosphere of Venus than in that of Earth? Why so much more carbon dioxide than on Mars?
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If the Viking missions were such a rich source of information about Mars, why have we sent the Pathfinder,
Global Surveyor
, and other more recent spacecraft to Mars? Make a list of questions about Mars that still puzzle astronomers.
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Compare Mars with Mercury and the Moon in terms of overall properties. What are the main similarities and differences?
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Contrast the mountains on Mars and Venus with those on Earth and the Moon.
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We believe that all of the terrestrial planets had similar histories when it comes to impacts from space. Explain how this idea can be used to date the formation of the martian highlands, the martian basins, and the Tharsis volcanoes. How certain are the ages derived for these features (in other words, how do we check the ages we derive from this method)?
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Is it likely that life ever existed on either Venus or Mars? Justify your answer in each case.
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Suppose that, decades from now, NASA is considering sending astronauts to Mars and Venus. In each case, describe what kind of protective gear they would have to carry, and what their chances for survival would be if their spacesuits ruptured.
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We believe that Venus, Earth, and Mars all started with a significant supply of water. Explain where that water is now for each planet.
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One source of information about Mars has been the analysis of meteorites from Mars. Since no samples from Mars have ever been returned to Earth from any of the missions we sent there, how do we know these meteorites are from Mars? What information have they revealed about Mars?
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The runaway greenhouse effect and its inverse, the runaway refrigerator effect, have led to harsh, uninhabitable conditions on Venus and Mars. Does the greenhouse effect always cause climate changes leading to loss of water and life? Give a reason for your answer.
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In what way is the high surface temperature of Venus relevant to concerns about global warming on Earth today?
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What is a dust devil? Would you expect to feel more of a breeze from a dust devil on Mars or on Earth? Explain.
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Near the martian equator, temperatures at the same spot can vary from an average of –135 °C at night to an average of 30 °C during the day. How can you explain such a wide difference in temperature compared to that on Earth?
Figuring for Yourself
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Estimate the amount of water there could be in a global (planet-wide) region of subsurface permafrost on Mars (do the calculations for two permafrost thicknesses, 1 and 10 km, and a concentration of ice in the permafrost of 10% by volume). Compare the two results you get with the amount of water in Earth’s oceans calculated in Example 10.5.1.
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At its nearest, Venus comes within about 41 million km of Earth. How distant is it at its farthest?
 On Mars?
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Calculate the relative land area—that is, the amount of the surface not covered by liquids—of Earth, the Moon, Venus, and Mars. (Assume that 70% of Earth is covered with water.)
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The closest approach distance between Mars and Earth is about 56 million km. Assume you can travel in a spaceship at 58,000 km/h, which is the speed achieved by the New Horizons space probe that went to Pluto and is the fastest speed so far of any space vehicle launched from Earth. How long would it take to get to Mars at the time of closest approach?