3.3B: Branches of Spinal Nerves
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The spinal nerves branch into the dorsal ramus, ventral ramus, the meningeal branches, and the rami communicantes.
Learning Objectives
- Describe branches of the peripheral nervous system
Key Points
- The dorsal and ventral rami contain nerves that provide visceral motor, somatic motor, and sensory information, with the dorsal ramus feeding the dorsal trunk (skin and muscles of the back), and the ventral ramus feeding the ventral trunk and limbs through the ventrolateral surface.
- The meningeal branches supply nerve function to the vertebrae themselves, including the ligaments, dura, blood vessels, intervertebral discs, facet joints, and periosteum.
- The rami communicantes contain autonomic nerves that carry visceral motor and sensory information to and from the visceral organs.
Key Terms
- nerve plexus : A branching network of intersecting nerves.
- dorsal ramus : The posterior (or dorsal) branches (or divisions) of the spinal nerves are, as a rule, smaller than the anterior divisions. They are also referred to as the dorsal rami. They are directed backwards and—with the exceptions of those of the first cervical, the fourth and fifth sacral, and the coccygeal—divide into medial and lateral branches for the supply of the muscles and skin of the posterior part of the trunk.
- meningeal branches : Also known as recurrent meningeal nerves, sinuvertebral nerves, or recurrent nerves of Luschka, these are a number of small nerves that branch from the spinal nerve (or the posterior ramus) near the origin of the anterior and posterior rami. They then re-enter the intervertebral foramen, and innervate the facet joints, the annulus fibrosus of the intervertebral disk, and the ligaments and periosteum of the spinal canal, carrying pain sensation.
Course and branches of thoracic spinal nerve : This diagram depicts the course and branches of a typical thoracic spinal nerve. The posterior division (dorsal ramus) is labeled at the top right.
Outside the vertebral column, the spinal nerves divide into branches.
- The dorsal ramus: Contains nerves that serve the dorsal portions of the trunk carrying visceral motor, somatic motor, and sensory information to and from the skin and muscles of the back.
- The ventral ramus: Contains nerves that serve the remaining ventral parts of the trunk and the upper and lower limbs carrying visceral motor, somatic motor, and sensory information to and from the ventrolateral body surface, structures in the body wall, and the limbs.
- Some ventral rami merge with adjacent ventral rami to form a nerve plexus, a network of interconnecting nerves. Nerves emerging from a plexus contain fibers from various spinal nerves, which are now carried together to some target location. Major plexuses include the cervical, brachial, lumbar, and sacral plexuses.
- The meningeal branches (recurrent meningeal or sinuvertebral nerves): These branch from the spinal nerve and re-enter the intervertebral foramen to serve the ligaments, dura, blood vessels, intervertebral discs, facet joints, and periosteum of the vertebrae.
- The rami communicantes: Contain autonomic nerves that carry visceral motor and sensory information to and from the visceral organs.


5.3: Level 1: Sorting and Classifying a Spider Collection and Assessing its Comprehensiveness
Obtain a paper copy of the spider collection for forest patch "1." The spiders were captured by a biologist traveling along transects through the patch and striking a random series of 100 tree branches. All spiders dislodged that fell onto an outstretched sheet were collected and preserved in alcohol. They have since been spread out on a tray for you to examine. The spider collection is hypothetical but the species pictured are actual spiders that occur in central Africa (illustrations used are from Berland 1955).
The next task is for you to sort and identify the spiders. To do this you have to identify all the specimens in the collection. To classify the spiders look for external characters that all members of a particular group of spiders have in common but that are not shared by other groups of spiders. For example, leg length, hairiness, relative size of body segments, or abdomen patterning and abdomen shape all might be useful characters. Look for groups of morphologically indistinguishable spiders, and describe briefly the set of characters unique to each group. These operational taxonomic units that you define will be considered separate species. To assist you in classifying these organisms, a diagram of key external morphological characters of beetles is provided ( Figure \(\PageIndex{1}\) ). Note that most spider identification depends on close examination of spider genitalia. For this exercise, however, we will be examining gross external characteristics of morphologically dissimilar species.
Figure \(\PageIndex{1}\) Basic external characteristics of spiders useful for identifying individuals to species.
Assign each species a working name, preferably something descriptive. For example, you might call a particular species "spotted abdomen, very hairy" or "short legs, spiky abdomen" Just remember that the more useful names will be those that signify to you something unique about the species. Construct a table listing each species, its distinguishing characteristics, the name you have applied to it, and the number of occurrences of the species in the collection ( Figure \(\PageIndex{2}\) ).
Figure \(\PageIndex{2}\)
Last, ask whether this collection adequately represents the true diversity of spiders in the forest patch at the time of collection. Were most of the species present sampled or were many likely missed? This is always an important question to ask to ensure that the sample was adequate and hence can be legitimately contrasted among sites to, for example, assign areas as low versus high diversity sites.
To do this you will perform a simple but informative analysis that is standard practice for conservation biologists who do biodiversity surveys. This analysis involves constructing a so-called collector's curve (Colwell and Coddington 1994). These plot the cumulative number of species observed (y-axis) against the cumulative number of individuals classified (x-axis). The collector's curve is an increasing function with a slope that will decrease as more individuals are classified and as fewer species remain to be identified ( Figure \(\PageIndex{3}\) ). If sampling stops while the collector's curve is still rapidly increasing, sampling is incomplete and many species likely remain undetected. Alternatively, if the slope of the collector's curve reaches zero (flattens out), sampling is likely more than adequate as few to no new species remain undetected.
Figure \(\PageIndex{3}\) An example of a collectors curve. Cumulative sample size represents the number of individuals classified. The cumulative number of taxa sampled refers to the number of new species detected.
To construct the collector's curve for this spider collection, choose a specimen within the collection at random. This will be your first data point, such that \(X=1\) and \(Y=1\) because after examining the first individual you have also identified one new species! Next move consistently in any direction to a new specimen and record whether it is a member of a new species. In this next step, \(X=2\), but \(Y\) may remain as 1 if the next individual is not of a new species or it may change to 2 if the individual represents a new species different from individual 1. Repeat this process until you have proceeded through all 50 specimens and construct the collector's curve from the data obtained (just plot \(Y\) versus \(X\)). Does the curve flatten out? If so, after how many individual spiders have been collected? If not, is the curve still increasing? What can you conclude from the shape of your collector's curve as to whether the sample of spiders is an adequate characterization of spider diversity at the site?


12.12: Earth's Energy
Much of Earth’s energy comes from the Sun. Nearly all life on Earth depends on solar energy since plants use sunlight to make food through the process of photosynthesis. Photosynthesis was the process that fed plants and animals, which in turn, over the course of millions of years, became fossil fuels. The Sun heats some areas of Earth more than other areas, which causes wind. The Sun’s energy also drives the water cycle, which moves water over the surface of the Earth. Some of these types of energy can be harnessed for use by people.
The other main source of energy is Earth’s internal heat. This heat has two origins: the breakdown of chemical elements by radioactivity, and the heat that is left over from when the planet came together. These two sources will be described in more detail in later chapters.
ENERGY RESOURCES
Everything requires energy. Even when you are sitting as still as you possibly can, your body is using energy to breathe, circulate blood, digest food, and perform many other functions. Producing light or heat requires energy. Making something requires energy. Plants and animals all require energy to function. To repeat, everything requires energy!
The Need for Energy
Energy is the ability to do work or produce change. Every living thing needs energy to perform its daily functions and even more energy to grow. Plants get energy from the “food” they make by photosynthesis, and animals get energy directly or indirectly from that food. People also use energy for many things, such as cooking food, keeping ice cream cold in the freezer, heating a house, constructing a skyscraper, or lighting their homes. Because billions of people all around the world use energy, there is a huge need for energy resources (figure 1). Energy conservation is something everyone can do now to help reduce the strain on energy resources.
Figure 1. Electrical transmission towers like the one shown in this picture help deliver the electricity people use for energy every day.
The law of conservation of energy says that energy cannot be created or destroyed. This means that even though energy changes form, the total amount of energy always stays the same. How does energy get converted from one type to another when you kick a soccer ball? When your body breaks down the food you eat, it stores the energy from the food as chemical energy . Chemical energy is stored within chemical bonds. But some of this stored energy has to be released to make your leg muscles move. The chemical energy is converted to another form of energy called kinetic energy . Kinetic energy is the energy of anything in motion. Your muscles move your leg, your foot kicks the ball, and the ball gains kinetic energy from the kick. So you can think of the action of kicking the ball as a story of energy changing forms.
To learn the quadratic equations related to getting a rapidly moving car to overcome its kinetic energy and come to a stop, watch this video:
Potential energy is energy that is stored. Potential energy has the potential to do work or the potential to be converted into other forms of energy. If a ball is sitting on the very edge at the top of the hill, it is not moving, but it has a lot of potential energy.
Animations showing the conversion of potential energy to kinetic energy can be seen at the following sites:
- Energy Transformation for Downhill Skiing
- Energy Transformation on a Roller Coaster
- Energy Transformation for a Dart
Energy, Fuel, and Heat
If you read a book beneath a lit lamp, that lamp has energy from electricity. The energy to make the electricity comes from fuel. Fuel has energy that it releases. A fuel is any material that can release energy in a chemical change.
What are some examples of fuel, and what are they used for?
- Food is fuel for your body.
- Sunlight is the energy plants need to make food by photosynthesis.
- Gasoline is fuel for cars.
- Hydrogen is fuel for the Sun.
For a fuel to be useful, its energy must be released in a way that can be controlled. Controlling the release of energy makes it possible for the energy to be used to do work. When fuel is used for its energy, it is usually burned, and most of the energy is released as heat (figure 2). The heat may then be used to do work. Think of a person striking a match to set some small twigs on fire.   Pretty soon the fire is roaring, and a pot of water placed on the fire starts to boil. Some of the liquid water evaporates.
Figure 2. A controlled fire.
What is the source of energy for boiling and evaporating the water? Although some chemical energy from the match was put into starting the fire, the heat to boil and evaporate the water comes from the energy that was stored in the wood. The wood is the fuel for the fire.
Types of Energy Resources
Energy resources are either renewable or non-renewable. Non-renewable resources are used faster than they can be replaced,so the supply available to society is limited (see example in figure 3). Renewable resources will not run out because they are replaced as quickly as they are used. Can you think of some renewable and non-renewable energy sources?
Figure 3. Anthracite coal is a non-renewable energy resource.
Non-Renewable Resources
Fossil fuels—coal, oil, and natural gas—are the most common example of non-renewable energy resources. Fossil fuels are formed from fossils, the partially decomposed remains of once living plants and animals. These fossils took millions of years to form. When fossil fuels are burned for energy, they release pollutants into the atmosphere. Fossil fuels also release carbon dioxide and other greenhouse gases, which are causing global temperatures to rise. The environmental effects of fossil fuel use are discussed in the “Climate” and “Human Actions and the Atmosphere” chapters.
Renewable Resources
Renewable energy resources include solar, water, wind, biomass, and geothermal. These resources are either virtually limitless like the Sun, which will continue to shine for billions of years, or will be replaced faster than we can use them. Amounts of falling water or wind will change over the course of time, but they are quite abundant. Biomass energy, like wood for fire, can be replaced quickly.
The use of renewable resources may also cause problems. Some are expensive, while some, such as trees, have other uses. Some cause environmental problems. As the technology improves and more people use renewable energy, the prices may come down. At the same time, as we use up fossil fuels, coal, oil, and natural gas, these non-renewable resources will become more expensive. At some point, even if renewable energy costs are high, non-renewable energy will be even more expensive. Ultimately, we will have to use renewable sources.
Important Things to Consider about Energy Resources
With both renewable and non-renewable resources, there are at least two important things to consider. One is that we have to have a practical way to turn the resource into a useful form of energy. The other is that we have to consider what happens when we turn the resource into energy.
For example, if we get much less energy from burning a fuel than we put into making it, then that fuel is probably not a practical energy resource. On the other hand, if another fuel gives us large amounts of energy but creates large amounts of pollution, that fuel also may not be the best choice for an energy resource.
Today we rely on electricity more than ever, but the resources that currently supply our power are finite. The race is on to harness more renewable resources, but getting all that clean energy from production sites to homes and businesses is proving to be a major challenge.
NON-RENEWABLE ENERGY RESOURCES
Millions of years ago, plants used energy from the Sun to form sugars, carbohydrates, and other energy-rich carbon compounds that were later transformed into coal, oil, or natural gas. The solar energy stored in these fuels is a rich source of energy. Although fossil fuels provide very high quality energy, they are non-renewable.
In large part, non-renewable energy sources are responsible for the world’s lights seen in this animation.
Formation of Fossil Fuels
Can you name some fossils? How about dinosaur bones or dinosaur footprints? Animal skeletons, teeth, shells, coprolites (otherwise known as feces), or any other remains or trace from a living creature that becomes a rock is a fossil .
Figure 4. This wetland may look something like an ancient coal-forming swamp.
The same processes that formed these fossils also created some of our most important energy resources, fossil fuels . Coal, oil, and natural gas are fossil fuels. Fossil fuels come from living matter starting about 500 million years ago. As plants and animals died, their remains settled on the ground on land and in swamps, lakes, and seas (figure 4).
Over time, layer upon layer of these remains accumulated. Eventually, the layers were buried so deeply that they were crushed by an enormous mass of earth. The weight of this earth pressing down on these plant and animal remains created intense heat and pressure. After millions of years of heat and pressure, the material in these layers turned into chemicals called hydrocarbons (figure 5). Here is an animated view of a hydrocarbon.
Figure 5. Hydrocarbons are made of carbon and hydrogen atoms. This molecule with one carbon and four hydrogen atoms is methane.
Hydrocarbons can be solid, liquid, or gaseous. The solid form is what we know as coal. The liquid form is petroleum, or crude oil. Natural gas is the gaseous form.
Coal
Coal, a solid fossil fuel formed from the partially decomposed remains of ancient forests, is burned primarily to produce electricity. Coal use is undergoing enormous growth as the availability of oil and natural gas decreases and cost increases. This increase in coal use is happening particularly in developing nations, such as China, where coal is cheap and plentiful.
Coal Formation
Coal forms from dead plants that settled at the bottom of ancient swamps. Lush coal swamps were common in the tropics during the Carboniferous period, which took place more than 300 million years ago (figure 6). The climate was warmer then.
Figure 6. The location of the continents during the Carboniferous period. Notice that quite a lot of land area is in the region of the tropics.
Mud and other dead plants buried the organic material in the swamp, and burial kept oxygen away. When plants are buried without oxygen, the organic material can be preserved or fossilized. Sand and clay settling on top of the decaying plants squeezed out the water and other substances. Millions of years later, what remains is a carbon-containing rock that we know as coal.
Figure 7. Bituminous coal is a sedimentary rock.
Coal is black or brownish-black. The most common form of coal is bituminous, a sedimentary rock that contains impurities such as sulfur (figure 7). Anthracite coal, seen in figure 3, has been metamorphosed and is nearly all carbon. For this reason, anthracite coal burns more cleanly than bituminous coal.
Coal Use
Around the world, coal is the largest source of energy for electricity. The United States is rich in coal (figure 8). California once had a number of small coal mines, but the state no longer produces coal. To turn coal into electricity, the rock is crushed into powder, which is then burned in a furnace that has a boiler. Like other fuels, coal releases its energy as heat when it burns. Heat from the burning coal boils the water in the boiler to make steam. The steam spins turbines, which turn generators to create electricity. In this way, the energy stored in the coal is converted to useful energy like electricity.
Figure 8. United States coal-producing regions in 1996. Orange is highest grade anthracite; red is low volatile bituminous; gray and gray-green is medium to high-volatile bituminous; green is subbituminous; and yellow is the lowest grade lignite
Coal that has been located but is not being used is part of our reserves. Reserves are important because if the price of the resource goes up or the cost of extracting it goes down, they may be useful.
Consequences of Coal Use
For coal to be used as an energy source, it must first be mined. Coal mining occurs at the surface or underground by methods that are described in the “Earth’s Minerals” chapter (figure 9). Mining, especially underground mining, can be dangerous. In April 2010, twenty-nine miners were killed at a West Virginia coal mine when gas that had accumulated in the mine tunnels exploded and started a fire.
Figure 9. The coal used in power plants must be mined. One method to mine coal is by mountaintop removal.
Some possible types of environmental damage from mining are discussed in the “Earth’s Minerals” chapter. Coal mining exposes minerals and rocks from underground to air and water at the surface. Many of these minerals contain the element sulfur, which mixes with air and water to make sulfuric acid, a highly corrosive chemical. If the sulfuric acid gets into streams, it can kill fish, plants, and animals that live in or near the water.
Oil
Oil is a liquid fossil fuel that is extremely useful because it can be transported easily and can be used in cars and other vehicles. Oil is currently the single largest source of energy in the world.
Oil Formation
Oil from the ground is called crude oil , which is a mixture of many different hydrocarbons. Crude oil is a thick dark brown or black liquid hydrocarbon.  The dead organisms are kept away from oxygen by layers of other dead creatures and sediments. As the layers pile up, heat and pressure increase. Over millions of years, the dead organisms turn into liquid oil.
Oil Production
In order to be collected, the oil must be located between a porous rock layer and an impermeable layer (figure 10). Trapped above the porous rock layer and beneath the impermeable layer, the oil will remain between these layers until it is extracted from the rock.
Figure 10. Oil (red) is found in the porous rock layer (yellow) and trapped by the impermeable layer (brown). The folded structure has allowed the oil to pool so a well can be drilled into the reservoir.
- Here is an animation of an oil deposit forming.
- The oil pocket is then drilled into from the surface. Here is an animation of an oil deposit being drilled.
- Sideways drilling allows a deposit that lies beneath land that cannot be drilled to be mined for oil.
To separate the different types of hydrocarbons in crude oil for different uses, the crude oil must be refined in refineries like the one shown in figure 11. Refining is possible because each hydrocarbon in crude oil boils at a different temperature. When the oil is boiled in the refinery, separate equipment collects the different compounds.
Figure 11. Refineries like this one separate crude oil into many useful fuels and other chemicals.
Oil Use
Most of the compounds that come out of the refining process are fuels, such as gasoline, diesel, and heating oil. Because these fuels are rich sources of energy and can be easily transported, oil provides about 90% of the energy used for transportation around the world. The rest of the compounds from crude oil are used for waxes, plastics, fertilizers, and other products.
Gasoline is in a convenient form for use in cars and other transportation vehicles. In a car engine, the burned gasoline mostly turns into carbon dioxide and water vapor. The fuel releases most of its energy as heat, which causes the gases to expand. This creates enough force to move the pistons inside the engine and to power the car.
Consequences of Oil Use
The United States does produce oil, but the amount produced is only about one-quarter as much as the nation uses. The United States has only about 1.5% of the world’s proven oil reserves, and so most of the oil used by Americans must be imported from other nations.
The main oil-producing regions in the United States are the Gulf of Mexico, Texas, Alaska, and California. Most offshore drilling occurs in the Gulf of Mexico, but there are offshore platforms in California as well (Figure 12). Here is an animation of the location of petroleum basins in the contiguous United States.
Figure 12. Offshore well locations in the Gulf of Mexico. Note that some wells are located in very deep water.
As in every type of mining, mining for oil has environmental consequences. Oil rigs are unsightly (figure 13), and spills are too common (figure 14).
Figure 13. Drill rigs at the San Ardo Oil Field in Monterey, California.
Figure 14. A deadly explosion on an oil rig in the Gulf of Mexico in April 2010 led to a massive oil spill. When this picture was taken in July 2010, oil was still spewing into the Gulf. The long-term consequences of the spill are being studied and are as yet unknown.
Natural Gas
Natural gas, often known simply as gas, is composed mostly of the hydrocarbon methane (refer to figure 5 for the structure).
Natural Gas Formation
Natural gas forms under the same conditions that create oil. Organic material buried in the sediments harden to become a shale formation that is the source of the gas. Although natural gas forms at higher temperatures than crude oil, the two are often found together. The formation of a minable oil and gas deposit is seen in this animation.
The largest natural gas reserves in the United States are in the Appalachian Basin, Texas, and the Gulf of Mexico region (Figure 15). California also has natural gas, found mostly in the Central Valley.  Here is an animation of global natural gas reserves.
Figure 15. Gas production in the Lower 48 United States.
Natural Gas Use
Like crude oil, natural gas must be processed before it can be used as a fuel. Some of the chemicals in unprocessed natural gas are poisonous to humans. Other chemicals, such as water, make the gas less useful as a fuel. Processing natural gas removes almost everything except the methane. Once the gas is processed, it is ready to be delivered and used. Natural gas is delivered to homes for uses such as cooking and heating. Like coal and oil, natural gas is also burned to generate heat for powering turbines. The spinning turbines turn generators, and the generators create electricity.
Consequences of Natural Gas Use
Natural gas burns much cleaner than other fossil fuels, meaning that it causes less air pollution. Natural gas also produces less carbon dioxide than other fossil fuels do for the same amount of energy, so its global warming effects are less (figure 16).
Figure 16. A natural gas drill rig.
Unfortunately, drilling for natural gas can be environmentally destructive. One technique used is hydraulic fracturing, also called fracking, which increases the rate of recovery of natural gas. Fluids are pumped through a borehole to create fractures in the reservoir rock that contains the natural gas. Material is added to the fluid to prevent the fractures from closing. The damage comes primarily from chemicals in the fracturing fluids. Chemicals that have been found in the fluids may be carcinogens (cancer-causing), radioactive materials, or endocrine disruptors, which interrupt hormones in the bodies of humans and animals. The fluids may get into groundwater or may runoff into streams and other surface waters.
Fossil Fuel Reserves
Fossil fuels provide about 85% of the world’s energy at this time. Worldwide fossil fuel usage has increased many times over in the past half century (coal: 2.6x, oil: 8x, natural gas: 14x) because of population increases, because of increases in the number of cars, televisions, and other fuel-consuming uses in the developed world, and because of lifestyle improvements in the developing world. Past and predicted use of different types of energy in the United States can be seen in this animation.
Figure 17. Worldwide oil reserves.
The amount of fossil fuels that remain untapped is unknown but can likely be measured in decades for oil and natural gas and in a few centuries for coal (figure 17). Alternative sources of fossil fuels, such as oil shales and tar sands, are increasingly being exploited (figure 18).
Figure 18. A satellite image of an oil-sands mine in Canada.
The environmental consequences of mining these fuels, and of fossil fuel use in general, along with the fact that these fuels do not have a limitless supply, are prompting the development of alternative energy sources.
Nuclear Energy
When the nucleus of an atom is split, it releases a huge amount of energy called nuclear energy. For nuclear energy to be used as a power source, scientists and engineers have learned to split nuclei and to control the release of energy (Figure 19).
Figure 19. When struck by a tiny particle, Uranium-235 breaks apart and releases energy.
Nuclear Energy Use
Nuclear power plants, such as the one seen in figure 20, use uranium, which is mined, processed, and then concentrated into fuel rods. When the uranium atoms in the fuel rods are hit by other extremely tiny particles, they split apart. The number of tiny particles allowed to hit the fuel rods needs to be controlled or they would cause a dangerous explosion. The energy from a nuclear power plant heats water, which creates steam and causes a turbine to spin. The spinning turbine turns a generator, which in turn produces electricity.
Figure 20. Nuclear power plants like this one provide France with almost 80% of its electricity.
Many countries around the world use nuclear energy as a source of electricity. In the United States, a little less than 20% of electricity comes from nuclear energy.
Consequences of Nuclear Power
Nuclear power is clean. It does not pollute the air or release carbon dioxide. However, the use of nuclear energy does create other environmental problems. Uranium must be mined (figure 21). The process of splitting atoms creates radioactive waste, which remains dangerous for thousands or hundreds of thousands of years. As yet, there is no long-term solution for storing this waste.
Figure 21. Uranium mine in Kakadu National Park, Australia.
The development of nuclear power plants has been on hold for three decades. Accidents at Three Mile Island and Chernobyl, Ukraine verified people’s worst fears about the dangers of harnessing nuclear power (figure 22).
Figure 22. Damaged building near the site of the Chernobyl disaster.
Recently, nuclear power appeared to be making a comeback as society looked for alternatives to fossil fuels. But the 2011 disaster at the Fukushima Daiichi Nuclear Power Plant in Japan may have resulted in a new fear of nuclear power. The cause of the disaster was a 9.0 magnitude earthquake and subsequent tsunami, which compromised the plant. Although a total meltdown was averted, the plant experienced multiple partial meltdowns, core breaches, radiation releases, and cooling failures. The plant is scheduled for a complete cold shutdown before the end of 2011.
KQED: Nuclear Energy Use. Nuclear power is a controversial subject in California and most other places. Nuclear power has no pollutants including carbon emissions, but power plants are not always safe and the long-term disposal of wastes is a problem that has not yet been solved. The future of nuclear power is murky.
RENEWABLE ENERGY RESOURCES
Fossil fuels have the advantage of being cheap and transportable, but they cause environmental damage and will eventually run out. Renewable energy sources, by definition, will not run out, and most do not cause much pollution. But renewable energy sources do have a downside, too. Both the advantages and disadvantages of solar, water, wind, biomass, and geothermal energy will be described in this lesson.
Solar Power
The Sun is Earth’s main source of energy, making the development of solar power a natural choice for an alternative energy source.
Solar Energy
Energy from the Sun comes from the lightest element, hydrogen, fusing together to create the second lightest element, helium. Nuclear fusion releases tremendous amounts of solar energy. The energy travels to the Earth, mostly as visible light. The light carries the energy through the empty space between the Sun and the Earth as radiation .
Solar Power Use
Solar energy has been used for power on a small scale for hundreds of years, and plants have used it for billions of year. Unlike energy from fossil fuels, which almost always come from a central power plant or refinery, solar power can be harnessed locally (figure 23). A set of solar panels on a home’s rooftop can be used to heat water for a swimming pool or can provide electricity to the house.
Figure 23. Solar panels supply power to the International Space Station.
Society’s use of solar power on a larger scale is just starting to increase. Scientists and engineers have very active, ongoing research into new ways to harness energy from the Sun more efficiently. Because of the tremendous amount of incoming sunlight, solar power is being developed in the United States in southeastern California, Nevada, and Arizona.
Solar power plants turn sunlight into electricity using a large group of mirrors to focus sunlight on one place, called a receiver (figure 24). A liquid, such as oil or water, flows through this receiver and is heated to a high temperature by the focused sunlight. The heated liquid transfers its heat to a nearby object that is at a lower temperature through a process called conduction . The energy conducted by the heated liquid is used to make electricity.
Figure 24. This solar power plant uses mirrors to focus sunlight on the tower in the center. The sunlight heats a liquid inside the tower to a very high temperature, producing energy to make electricity.
Here’s a video of how solar energy can be concentrated so that it can be used for power.
Consequences of Solar Power Use
Solar energy has many benefits. It is extremely abundant, widespread, and will never run out. But there are problems with the widespread use of solar power.
Figure 25. This experimental car is one example of the many uses that engineers have found for solar energy.
- Sunlight must be present. Solar power is not useful in locations that are often cloudy or at night. However, storage technology is being developed.
- The technology needed for solar power is still expensive. An increase in interested customers will provide incentive for companies to research and develop new technologies and to figure out how to mass-produce existing technologies (figure 25).
- Solar panels require a lot of space. Fortunately, solar panels can be placed on any rooftop to supply at least some of the power required for a home or business.
Water Power
Water covers 70% of the planet’s surface, and water power (hydroelectric power) is the most widely used form of renewable energy in the world. Hydroelectric power from streams provides almost one fifth of the world’s electricity.
Hydroelectric Power
Remember that potential energy is the energy of an object waiting to fall. Water held behind a dam has a lot of potential energy. In a hydroelectric plant, a dam across a riverbed holds a stream to create a reservoir. Instead of flowing down its normal channel, the water is allowed to flow into a large turbine. As the water moves, it has kinetic energy, which makes the turbine spin. The turbine is connected to a generator, which makes electricity (figure 26).
Figure 26. A cross-section of a hydroelectric plant.
Most of the streams in the United States and elsewhere in the developed world that are suitable for hydroelectric power have already been dammed (figure 27). In California, about 14.5% of the total electricity comes from hydropower. The state’s nearly 400 hydropower plants are mostly located in the eastern mountain ranges where large streams descend down a steep grade.
Figure 27. Hydroelectric dams like this one use the power of moving water to create electricity.
Consequences of Water Power Use
The major benefit of hydropower is that it generates power without releasing any pollution. Hydropower is also a renewable resource since the stream will keep on flowing. However, there are a limited number of suitable dam sites. Hydropower also has environmental problems. When a large dam disrupts a river’s flow, it changes the ecosystem upstream. As the land is flooded by rising water, plants and animals are displaced or killed. Many beautiful landscapes, villages, and archeological sites have been drowned by the water in a reservoir (figure 28).
Figure 28. Glen Canyon Dam in Arizona created Lake Powell. The dam was controversial because it flooded Glen Canyon, a beautiful desert canyon.
The dam and turbines also change the downstream environment for fish and other living things. Dams slow the release of silt so that downstream deltas retreat and seaside cities become dangerously exposed to storms and rising sea levels.
Ocean Water Power
The energy of waves and tides can be used to produce water power. Tidal power stations may need to close off a narrow bay or estuary. Wave power applications have to be able to withstand coastal storms and the corrosion of seawater. Because of the many problems with them, tide and wave power plants are not very common.
KQED: Harnessing Power from the Sea. Although not yet widely used, many believe tidal power has more potential than wind or solar power for meeting alternative energy needs. Quest radio looks at plans for harnessing power from the sea by San Francisco and along the northern California coast.
Wind Power
Wind power is the fastest growing renewable energy source in the world. Windmills are now seen in many locations, either individually or, more commonly, in large fields. Wind Powering America follows the development of wind power in the United States over the past several years.
Wind Energy
Energy from the sun also creates wind, which can be used as wind power. The sun heats different locations on Earth by different amounts.  The movement of air from one spot to another along the ground creates wind. Since wind is moving, it has kinetic energy.
Wind Power Use
Wind is the source of energy for wind power. Wind has been used for power for centuries. For example, windmills were used to grind grain and pump water. Sailing ships traveled by wind power long before ships were powered by fossil fuels. Wind can be used to generate electricity, as the moving air spins a turbine to create electricity (figure 29). This animation shows how wind power works.
Figure 29. Wind turbines like the ones shown here turn wind into electricity without creating pollution.
Consequences of Wind Power
Wind power has many advantages. It does not burn, so it does not release pollution or carbon dioxide. Also, wind is plentiful in many places. Wind, however, does not blow all of the time, even though power is needed all of the time. Just as with solar power, engineers are working on technologies that can store wind power for later use.
Windmills are expensive and wear out quickly. A lot of windmills are needed to power a region, so nearby residents may complain about the loss of a nice view if a wind farm is built. Coastlines typically receive a lot of wind, but wind farms built near beaches may cause unhappiness for local residents and tourists.
The Cape Wind Project off of Cape Cod has been approved but is generating much controversy. Opponents are in favor of green power but not at that location. Proponents say that clean energy is needed and the project would supply 75% of the electricity needed for Cape Cod and nearby islands (figure 30).
Figure 30. Cape Wind off of Cape Cod in Massachusetts receives a great deal of wind (red color) but is also popular with tourists for its beauty.
California was an early adopter of wind power. Windmills are found in mountain passes where the cooler Pacific Ocean air is sucked through on its way to warmer inland valleys. Large fields of windmills can be seen at Altamont pass in the eastern San Francisco Bay Area, San Gorgonio Pass east of Los Angeles, and Tehachapi Pass at the southern end of the San Joaquin Valley.
Geothermal Power
Geothermal energy comes from heat deep below the surface of the Earth. Nothing must be done to the geothermal energy. It is a resource that can be used without processing.
Geothermal Energy
The heat that is used for geothermal power may come to the surface naturally as hot springs or geysers, like The Geysers in northern California. Where water does not naturally come to the surface, engineers may pump cool water into the ground. The water is heated by the hot rock and then pumped back to the surface for use. The hot water or steam from a geothermal well spins a turbine to make electricity.
Geothermal energy is clean and safe. The energy source is renewable since hot rock is found everywhere in the Earth, although in many parts of the world the hot rock is not close enough to the surface for building geothermal power plants. In some areas, geothermal power is common (figure 31).
Figure 31. A geothermal energy plant in Iceland. Iceland gets about one fourth of its electricity from geothermal sources.
In the United States, California is a leader in producing geothermal energy. The largest geothermal power plant in the state is in the Geysers Geothermal Resource Area in Napa and Sonoma Counties, north of San Francisco. The source of heat is thought to be a large magma chamber lying beneath the area.
KQED: Geothermal Heats Up. Where Earth’s internal heat gets close to the surface, geothermal power is a clean source of energy. In California, The Geysers supplies energy for many nearby homes and businesses.
Biomass
Biomass is the material that comes from plants and animals that were recently living. Biomass can be burned directly, such as setting fire to wood. For as long as humans have had fire, people have used biomass for heating and cooking. People can also process biomass to make fuel, called biofuel. Biofuel can be created from crops, such as corn or algae, and processed for use in a car (figure 32). The advantage to biofuels is that they burn more cleanly than fossil fuels. As a result, they create less pollution and less carbon dioxide. Critics say, however, that the amount of energy, fertilizer, and land needed to produce the crops used make biofuels only a slightly better alternative than fossil fuels.
Figure 32. Biofuels, such as ethanol, are added to gasoline to cut down the amount of fossil fuels that are used.
- KQED: How Green is Biomass Energy? Organic material, like almond shells, can be made into electricity. Biomass power is a great use of wastes and is more reliable than other renewable energy sources, but harvesting biomass energy uses energy and biomass plants produce pollutants including greenhouse gases.
- KQED: From Waste to Watts: Biofuel Bonanza. Cow manure can have a second life as a source of methane gas, which can be converted to electricity. Not only that food scraps can also be converted into green energy.
- KQED: Biofuels: Beyond Ethanol. To generate biomass energy, break down the cell walls of plants to release the sugars and then ferment those sugars to create fuel. Corn is a very inefficient source; scientists are looking for much better sources of biomass energy.
- Algae Power. Many people think that the best source of biomass energy for the future is algae. Compared to corn, algae is not a food crop, it can grow in many places, its much easier to convert to a usable fuel and its carbon neutral.
- Power Up with Leftovers. Food that is tossed out produces methane, a potent greenhouse gas. But that methane from leftovers can be harnessed and used as fuel. Sounds like a win-win situation.
LESSON SUMMARY
- According to the law of conservation of energy, energy is neither created nor destroyed.
- Renewable resources can be replaced at the rate they are being used.
- Non-renewable resources are available in limited amounts or are being used faster than they can be replaced.
- Fossil fuels are non-renewable sources of energy that produce environmental damage.
- Coal, oil, and natural gas are fossil fuels formed from the remains of living organisms.
- Coal is the largest source of energy for producing electricity.
- Oil and natural gas are important energy sources for vehicles and electricity generation.
- Nuclear energy is produced by splitting atoms. It also produces radioactive wastes that are very dangerous for many years.
- Solar energy, water power, wind power, geothermal energy, and biomass energy are renewable energy sources.
- Solar energy can be used either by passively storing and holding the Sun’s heat, converting it to electricity, or concentrating it.
- There are many ways to use the energy of moving water, including hydroelectric dams and tidal and wave plants.
- Wind power uses the energy of moving air to turn turbines.
- Geothermal energy uses heat from deep within the earth to heat homes or produce steam that turns turbines.
- Biomass energy uses renewable materials such as wood or grains to produce energy.
REFLECTION QUESTIONS
- What skill does this content help you develop?
- What are the key topics covered in this content?
- How can the content in this section help you demonstrate mastery of a specific skill?
- What questions do you have about this content?
Contributors and Attributions
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Original content from Kimberly Schulte (Columbia Basin College) and supplemented by Lumen Learning . The content on this page is copyrighted under a Creative Commons Attribution 4.0 International license.


7.9: Content Theories of Motivation
Describe a content theory of motivation.
The theories presented in this section focus on the importance of human needs. A common thread through all of them is that people have a variety of needs. A need is a human condition that becomes “energized” when people feel deficient in some respect. When we are hungry, for example, our need for food has been energized. Two features of needs are key to understanding motivation. First, when a need has been energized, we are motivated to satisfy it. We strive to make the need disappear. Hedonism, one of the first motivation theories, assumes that people are motivated to satisfy mainly their own needs (seek pleasure, avoid pain). Long since displaced by more refined theories, hedonism clarifies the idea that needs provide direction for motivation. Second, once we have satisfied a need, it ceases to motivate us. When we’ve eaten to satiation, we are no longer motivated to eat. Other needs take over and we endeavor to satisfy them. A manifest need is whatever need is motivating us at a given time. Manifest needs dominate our other needs.
Instincts are our natural, fundamental needs, basic to our survival. Our needs for food and water are instinctive. Many needs are learned. We are not born with a high (or low) need for achievement—we learn to need success (or failure). The distinction between instinctive and learned needs sometimes blurs; for example, is our need to socialize with other people instinctive or learned?
Manifest Needs Theory
One major problem with the need approach to motivation is that we can make up a need for every human behavior. Do we “need” to talk or be silent? The possibilities are endless. In fact, around the 1920s, some 6,000 human needs had been identified by behavioral scientists!
Henry A. Murray recognized this problem and condensed the list into a few instinctive and learned needs. 3 Instincts, which Murray called primary needs , include physiological needs for food, water, sex (procreation), urination, and so on. Learned needs, which Murray called secondary needs , are learned throughout one’s life and are basically psychological in nature. They include such needs as the need for achievement, for love, and for affiliation (see Table \(\PageIndex{1}\)). 4
Sample Items from Murray's List of Needs
| Social Motive | Brief Definition |
|---|---|
| Source: Adapted from C. S. Hall and G. Lindzey, Theories of Personality. Sample items from Murray’s List of Needs. Copyright 1957 by John Wiley & Sons, New York. | |
| Abasement | To submit passively to external force. To accept injury, blame, criticism, punishment. To surrender. |
| Achievement | To accomplish something difficult. To master, manipulate, or organize physical objects, human beings, or ideas. |
| Affiliation | To draw near and enjoyably cooperate or reciprocate with an allied other (an other who resembles the subject or who likes the subject). To please and win affection of a coveted object. To adhere and remain loyal to a friend. |
| Aggression | To overcome opposition forcefully. To fight. To revenge an injury. To attack, injure, or kill another. To oppose forcefully or punish another. |
| Autonomy | To get free, shake off restraint, break out of confinement. |
| Counteraction | To master or make up for a failure by restriving. |
| Defendance | To defend the self against assault, criticism, and blame. To conceal or justify a misdeed, failure, or humiliation. To vindicate the ego. |
| Deference | To admire and support a superior. To praise, honor, or eulogize. |
| Dominance | To control one’s human environment. To influence or direct the behavior of others by suggestion, seduction, persuasion, or command. |
| Exhibition | To make an impression. To be seen and heard. To excite, amaze, fascinate, entertain, shock, intrigue, amuse, or entice others. |
| Harm avoidance | To avoid pain, physical injury, illness, and death. To escape from a dangerous situation. To take precautionary measures. |
| Infavoidance | To avoid humiliation. To quit embarrassing situations or to avoid conditions that may lead to belittlement or the scorn or indifference of others. |
| Nurturance | To give sympathy and gratify the needs of a helpless object: an infant or any object that is weak, disabled, tired, inexperienced, infirm, defeated, humiliated, lonely, dejected, sick, or mentally confused. To assist an object in danger. To feed, help, support, console, protect, comfort, nurse, heal. |
| Order | To put things in order. To achieve cleanliness, arrangement, organization, balance, neatness, tidiness, and precision. |
| Play | To act for “fun” without further purpose. To like to laugh and make jokes. To seek enjoyable relaxation from stress. |
| Rejection | To separate oneself from a negatively valued object. To exclude, abandon, expel, or remain indifferent to an inferior object. To snub or jilt an object. |
| Sentience | To seek and enjoy sensuous impressions. |
| Sex | To form and further an erotic relationship. To have sexual intercourse. |
| Succorance | To have one’s needs gratified by the sympathetic aid of an allied object. |
| Understanding | To ask or answer general questions. To be interested in theory. To speculate, formulate, analyze, and generalize. |
Murray’s main premise was that people have a variety of needs, but only a few are expressed at a given time. When a person is behaving in a way that satisfies some need, Murray called the need manifest. Manifest needs theory assumes that human behavior is driven by the desire to satisfy needs. Lucretia’s chattiness probably indicates her need for affiliation. This is a manifest need. But what if Lucretia also has a need to dominate others? Could we detect that need from her current behavior? If not, Murray calls this a latent need. A latent need cannot be inferred from a person’s behavior at a given time, yet the person may still possess that need. The person may not have had the opportunity to express the need. Or she may not be in the proper environment to solicit behaviors to satisfy the need. Lucretia’s need to dominate may not be motivating her current behavior because she is with friends instead of coworkers.
Manifest needs theory laid the groundwork for later theories, most notably McClelland’s learned needs theory, that have greatly influenced the study of organizational behavior. The major implication for management is that some employee needs are latent. Managers often assume that employees do not have certain needs because the employees never try to satisfy them at work. Such needs may exist (latent needs); the work environment is simply not conducive to their manifestation (manifest needs). A reclusive accountant may not have been given the opportunity to demonstrate his need for achievement because he never received challenging assignments.
Learned Needs Theory
David C. McClelland and his associates (especially John W. Atkinson) built on the work of Murray for over 50 years. Murray studied many different needs, but very few in any detail. McClelland’s research differs from Murray’s in that McClelland studied three needs in-depth: the need for achievement, the need for affiliation, and the need for power (often abbreviated, in turn, as nAch, nAff, and nPow). 5 McClelland believes that these three needs are learned, primarily in childhood. But he also believes that each need can be taught, especially nAch. McClelland’s research is important because much of the current thinking about organizational behavior is based on it.
Need for Achievement
The need for achievement (nAch) is how much people are motivated to excel at the tasks they are performing, especially tasks that are difficult. Of the three needs studied by McClelland, nAch has the greatest impact. The need for achievement varies in intensity across individuals. This makes nAch a personality trait as well as a statement about motivation. When nAch is being expressed, making it a manifest need, people try hard to succeed at whatever task they’re doing. We say these people have a high achievement motive. A motive is a source of motivation; it is the need that a person is attempting to satisfy. Achievement needs become manifest when individuals experience certain types of situations.
To better understand the nAch motive, it’s helpful to describe high-nAch people. You probably know a few of them. They’re constantly trying to accomplish something. One of your authors has a father-in-law who would much rather spend his weekends digging holes (for various home projects) than going fishing. Why? Because when he digs a hole, he gets results. In contrast, he can exert a lot of effort and still not catch a fish. A lot of fishing, no fish, and no results equal failure!
McClelland describes three major characteristics of high-nAch people:
- They feel personally responsible for completing whatever tasks they are assigned. They accept credit for success and blame for failure.
- They like situations where the probability of success is moderate. High-nAch people are not motivated by tasks that are too easy or extremely difficult. Instead, they prefer situations where the outcome is uncertain, but in which they believe they can succeed if they exert enough effort. They avoid both simple and impossible situations.
- They have very strong desires for feedback about how well they are doing. They actively seek out performance feedback. It doesn’t matter whether the information implies success or failure. They want to know whether they have achieved or not. They constantly ask how they are doing, sometimes to the point of being a nuisance.
Why is nAch important to organizational behavior? The answer is, the success of many organizations is dependent on the nAch levels of their employees. 6 This is especially true for jobs that require self-motivation and managing others. Employees who continuously have to be told how to do their jobs require an overly large management team, and too many layers of management spell trouble in the current marketplace. Today’s flexible, cost-conscious organizations have no room for top-heavy structures; their high-nAch employees perform their jobs well with minimal supervision.
Many organizations manage the achievement needs of their employees poorly. A common perception about people who perform unskilled jobs is that they are unmotivated and content doing what they are doing. But, if they have achievement needs, the job itself creates little motivation to perform. It is too easy. There are not enough workers who feel personal satisfaction for having the cleanest floors in a building. Designing jobs that are neither too challenging nor too boring is key to managing motivation. Job enrichment is one effective strategy; this frequently entails training and rotating employees through different jobs, or adding new challenges.
Need for Affiliation
This need is the second of McClelland’s learned needs. The need for affiliation (nAff) reflects a desire to establish and maintain warm and friendly relationships with other people. As with nAch, nAff varies in intensity across individuals. As you would expect, high-nAff people are very sociable. They’re more likely to go bowling with friends after work than to go home and watch television. Other people have lower affiliation needs. This doesn’t mean that they avoid other people, or that they dislike others. They simply don’t exert as much effort in this area as high-nAff people do.
The nAff has important implications for organizational behavior. High-nAff people like to be around other people, including other people at work. As a result, they perform better in jobs that require teamwork. Maintaining good relationships with their coworkers is important to them, so they go to great lengths to make the workgroup succeed because they fear rejection. So, high-nAff employees will be especially motivated to perform well if others depend on them. In contrast, if high-nAff people perform jobs in isolation from other people, they will be less motivated to perform well. Performing well on this job won’t satisfy their need to be around other people.
Effective managers carefully assess the degree to which people have high or low nAff. Employees high in nAff should be placed in jobs that require or allow interactions with other employees. Jobs that are best performed alone are more appropriate for low-nAff employees, who are less likely to be frustrated.
Need for Power
The third of McClelland’s learned needs, the need for power (nPow) , is the need to control things, especially other people. It reflects a motivation to influence and be responsible for other people. An employee who is often talkative, gives orders, and argues a lot is motivated by the need for power over others.
Employees with high nPow can be beneficial to organizations. High-nPow people do have effective employee behaviors, but at times they’re disruptive. A high-nPow person may try to convince others to do things that are detrimental to the organization. So, when is this need good, and when is it bad? Again, there are no easy answers. McClelland calls this the “two faces of power.” 7 A personal power seeker endeavors to control others mostly for the sake of dominating them. They want others to respond to their wishes whether or not it is good for the organization. They “build empires,” and they protect them.
McClelland’s other power seeker is the social power seeker. A high social power seeker satisfies needs for power by influencing others, like the personal power seeker. They differ in that they feel best when they have influenced a workgroup to achieve the group’s goals, and not some personal agenda. High social power-seekers are concerned with goals that a workgroup has set for itself, and they are motivated to influence others to achieve the goal. This need is oriented toward fulfilling responsibilities to the employer, not to the self.
McClelland has argued that the high need for social power is the most important motivator for successful managers. Successful managers tend to be high in this type of nPow. High need for achievement can also be important, but it sometimes results in too much concern for personal success and not enough for the employer’s success. The need for affiliation contributes to managerial success only in those situations where the maintenance of warm group relations is as important as getting others to work toward group goals.
The implication of McClelland’s research is that organizations should try to place people with high needs for social power in managerial jobs. It is critical, however, that those managerial jobs allow the employee to satisfy the nPow through social power acquisition. Otherwise, a manager high in nPow may satisfy this need through the acquisition of personal power, to the detriment of the organization.
Ethics in Practice
Corporate Social Responsibility as a Motivating Force
Whatever their perspective, most people have a cause that they are passionate about. Bitcoin or net neutrality, sea levels or factory farming—social causes bind us to a larger context or assume a higher purpose for living better.
So what motivates employees to give their all, work creatively, and be fully engaged? According to CB Bhattacharya, the Pietro Ferrero Chair in Sustainability at ESMT European School of Management and Technology in Berlin, Germany, employment engagement, or how positive employees feel about their current job, was at an all-time low globally in 2016: 13 percent. But not all companies battle such low engagement rates. Unilever employees more than 170,000 workers globally and has an employ engagement level around 80 percent. How? Bhattacharya credits the success of Unilever, and other companies with similar engagement levels, to an emphasis on a “sustainable business model.” He outlines eight steps that companies take to move sustainability and social responsibility from buzzwords to a company mission capable of motivating employees (Knowledge @ Wharton 2016).
According to Bhattacharya, a company needs to first define what it does and its long-term purpose, and then reconcile its sustainability goals with its economic goals. With its purpose and goals defined, it can then educate the workforce on sustainable methods to create knowledge and competence. Champions for the effort must be found throughout the organization, not just at the top. Competition should be encouraged among employees to find and embrace new goals. Sustainability should be visible both within and outside the company. Sustainability should be tied to a higher purpose and foster a sense of unity not simply among employees, but even with competition at a societal level (Knowledge @ Wharton 2016).
Other companies have made social responsibility an everyday part of what they do. Launched in 2013, Bombas is the brainchild of Randy Goldberg and David Heath. Goldberg and Heath discovered that socks are the most-requested clothing at homeless shelters. In response, the two entrepreneurs launched a line of socks that not only “reinvents” the sock (they claim), but also helps those in need. For each pair of socks purchased, the company donates a pair of socks to someone in need (Mulvey 2017). According to the company website, “Bombas exists to help solve this problem, to support the homeless community, and to bring awareness to an under-publicized problem in the United States” (n.p.). Although the New York-based company is still growing, as of October 2017 Bombas had donated more than four million pairs of socks (Bombas 2017).
In 2016, the Royal Bank of Scotland (RBS) launched a pilot program called Jump in which employees participated in challenges on ways to save water and electricity, as well as other sustainability issues. At the end of the pilot, 95 percent of the employees reported that they felt the program had contributed to employee engagement, team building, and environmental stability. Given the success of the program, in 2017 it was expanded to all RBS sites and a smartphone app was added to help employees participate in the challenges (Barton 2017).
Placing a company in a larger context and adding a second, higher purpose than the established company goals motivates employees to police the company itself to be a better global citizen. Companies benefit from reduced waste and increased employee engagement. Many companies are successfully motivating their staff, and working toward more sustainable practices, while improving lives directly.
Sources:
Barton, Tynan. 2017. “RBS boosts employee motivation and engagement through its CSR approach.” employee benefits. https://www.employeebenefits.co.uk/i...-csr-approach/
Bombas. 2017. “Giving Back.” https://bombas.com/pages/giving-back
Knowledge @ Wharton. 2016. “How Companies Can Tap Sustainability to Motivate Staff.” http://knowledge.wharton.upenn.edu/a...otivate-staff/
Mulvey, Kelsey. 2017. “This company spent two years perfecting gym socks, and it paid off.” Business Insider. http://www.businessinsider.com/bomba...-review-2017-1
Questions:
- Do you think social responsibility to promote sustainable practices? Why or why not?
- Do you think most companies’ CSR programs are essentially PR gimmicks? Why or why not? Give examples.
Maslow’s Hierarchy of Needs
Any discussion of needs that motivate performance would be incomplete without considering Abraham Maslow. 8 Thousands of managers in the 1960s were exposed to Maslow’s theory through the popular writings of Douglas McGregor. 9 Today, many of them still talk about employee motivation in terms of Maslow’s theory.
Maslow was a psychologist who, based on his early research with primates (monkeys), observations of patients, and discussions with employees in organizations, theorized that human needs are arranged hierarchically. That is, before one type of need can manifest itself, other needs must be satisfied. For example, our need for water takes precedence over our need for social interaction (this is also called prepotency ). We will always satisfy our need for water before we satisfy our social needs; water needs have prepotency over social needs. Maslow’s theory differs from others that preceded it because of this hierarchical, prepotency concept.
Maslow went on to propose five basic types of human needs. This is in contrast to the thousands of needs that earlier researchers had identified, and also fewer than Murray identified in his theory. Maslow condensed human needs into a manageable set. Those five human needs, in the order of prepotency in which they direct human behavior, are:
- Physiological and survival needs. These are the most basic of human needs and include the needs for water, food, sex, sleep, activity, stimulation, and oxygen.
- Safety and security needs. These needs invoke behaviors that assure freedom from danger. This set of needs involves meeting threats to our existence, including extremes in environmental conditions (heat, dust, and so on), assault from other humans, tyranny, and murder. In other words, satisfaction of these needs prevents fear and anxiety while adding stability and predictability to life.
- Social needs. These needs reflect human desires to be the target of affection and love from others. They are especially satisfied by the presence of spouses, children, parents, friends, relatives, and others to whom we feel close. Feelings of loneliness and rejection are symptoms that this need has not been satisfied.
- Ego and esteem. Esteem needs to go beyond social needs. They reflect our need to be respected by others, and to have esteem for ourselves. It is one thing to be liked by others. It is another thing to be respected for our talents and abilities. Ego and esteem needs have internal (self) and external (others) focuses. An internal focus includes desires for achievement, strength, competence, confidence, and independence. An external focus includes desires to have prestige, recognition, appreciation, attention, and respect from others. Satisfaction of external esteem needs can lead to satisfaction of internal esteem needs.
- Self-actualization. Self-actualization needs are the most difficult to describe. Unlike the other needs, the need for self-actualization is never completely satisfied. Self-actualization involves a desire for self-fulfillment, “to become more and more what one is, to become everything that one is capable of becoming.” 10 Because people are so different in their strengths and weaknesses, in capacities and limitations, the meaning of self-actualization varies greatly. Satisfying self-actualization needs means developing all of our special abilities to their fullest degree.
Figure \(\PageIndex{2}\) A protester at an anti-war demonstration in Seattle held up this sign. Where would you place that on Maslow’s hierarchy of needs?
Figure \(\PageIndex{3}\) illustrates Maslow’s proposed hierarchy of needs. According to his theory, people first direct their attention to satisfying their lower-order needs. Those are the needs at the bottom of the pyramid (physiological, safety, and security). Once those needs have been satisfied, the next level, social needs, becomes energized. Once satisfied, we focus on our ego and esteem needs. Maslow believed that most people become fixated at this level. That is, most people spend much of their lives developing self-esteem and the esteem of others. But, once those esteem needs are satisfied, Maslow predicted that self-actualization needs would dominate. There are no higher levels in the pyramid, because self-actualization needs can never be fully satisfied. They represent a continuing process of self-development and self-improvement that, once satisfied on one dimension (painting), create motivation to continue on other dimensions (sculpting). One wonders if athletes like Tim Tebow are self-actualizing when they participate in multiple sporting endeavors at the professional level.
An overriding principle in this theory is that a person’s attention (direction) and energy (intensity) will focus on satisfying the lowest-level need that is not currently satisfied. Needs can also be satisfied at some point but become active (dissatisfied) again. Needs must be “maintained” (we must continue to eat occasionally). According to Maslow, when lower-level needs are reactivated, we once again concentrate on that need. That is, we lose interest in the higher-level needs when lower-order needs are energized.
The implications of Maslow’s theory for organizational behavior are as much conceptual as they are practical. The theory posits that to maximize employee motivation, employers must try to guide workers to the upper parts of the hierarchy. That means that the employer should help employees satisfy lower-order needs like safety and security and social needs. Once satisfied, employees will be motivated to build esteem and respect through their work achievements. Exhibit 7.6 shows how Maslow’s theory relates to factors that organizations can influence. For example, by providing adequate pay, safe working conditions, and cohesive work groups, employers help employees satisfy their lower-order needs. Once satisfied, challenging jobs, additional responsibilities, and prestigious job titles can help employees satisfy higher-order esteem needs.
Maslow’s theory is still popular among practicing managers. Organizational behavior researchers, however, are not as enamored with it because research results don’t support Maslow’s hierarchical notion. Apparently, people don’t go through the five levels in a fixed fashion. On the other hand, there is some evidence that people satisfy the lower-order needs before they attempt to satisfy higher-order needs. Refinements of Maslow’s theory in recent years reflect this more limited hierarchy. 11 The self-assessment below will allow you to evaluate the strength of your five needs.
Alderfer’s ERG Theory
Clayton Alderfer observed that very few attempts had been made to test Maslow’s full theory. Further, the evidence accumulated provided only partial support. During the process of refining and extending Maslow’s theory, Alderfer provided another need-based theory and a somewhat more useful perspective on motivation. 12 Alderfer’s ERG theory compresses Maslow’s five need categories into three: existence, relatedness, and growth. 13 In addition, ERG theory details the dynamics of an individual’s movement between the need categories in a somewhat more detailed fashion than typically characterizes interpretations of Maslow’s work.
As shown in Figure \(\PageIndex{4}\), the ERG model addresses the same needs as those identified in Maslow’s work:
- Existence needs include physiological and material safety needs. These needs are satisfied by material conditions and not through interpersonal relations or personal involvement in the work setting.
- Relatedness needs include all of Maslow’s social needs, plus social safety and social esteem needs. These needs are satisfied through the exchange of thoughts and feelings with other people.
- Growth needs include self-esteem and self-actualization needs. These needs tend to be satisfied through one’s full involvement in work and the work setting.
Figure \(\PageIndex{5}\) identifies a number of ways in which organizations can help their members satisfy these three needs.
Four components—satisfaction progression, frustration, frustration regression, and aspiration—are key to understanding Alderfer’s ERG theory. The first of these, satisfaction progression, is in basic agreement with Maslow’s process of moving through the needs. As we increasingly satisfy our existence needs, we direct energy toward relatedness needs. As these needs are satisfied, our growth needs become more active. The second component, frustration, occurs when we attempt but fail to satisfy a particular need. The resulting frustration may make satisfying the unmet need even more important to us—unless we repeatedly fail to satisfy that need. In this case, Alderfer’s third component, frustration regression, can cause us to shift our attention to a previously satisfied, more concrete, and verifiable need. Lastly, the aspiration component of the ERG model notes that, by its very nature, growth is intrinsically satisfying. The more we grow, the more we want to grow. Therefore, the more we satisfy our growth need, the more important it becomes and the more strongly we are motivated to satisfy it.
Alderfer’s model is potentially more useful than Maslow’s in that it doesn’t create false motivational categories. For example, it is difficult for researchers to ascertain when interaction with others satisfies our need for acceptance and when it satisfies our need for recognition. ERG also focuses attention explicitly on movement through the set of needs in both directions. Further, evidence in support of the three need categories and their order tends to be stronger than evidence for Maslow’s five need categories and their relative order.
Herzberg’s Motivator-Hygiene Theory
Clearly one of the most influential motivation theories throughout the 1950s and 1960s was Frederick Herzberg’s motivator-hygiene theory. 14 This theory is a further refinement of Maslow’s theory. Herzberg argued that there are two sets of needs, instead of the five sets theorized by Maslow. He called the first set “motivators” (or growth needs). Motivators , which relate to the jobs we perform and our ability to feel a sense of achievement as a result of performing them, are rooted in our need to experience growth and self-actualization. The second set of needs he termed “hygienes.” Hygienes relate to the work environment and are based in the basic human need to “avoid pain.” According to Herzberg, growth needs motivate us to perform well and, when these needs are met, lead to the experience of satisfaction. Hygiene needs, on the other hand, must be met to avoid dissatisfaction (but do not necessarily provide satisfaction or motivation). 15
Hygiene factors are not directly related to the work itself (job content). Rather, hygienes refer to job context factors (pay, working conditions, supervision, and security). Herzberg also refers to these factors as “dissatisfiers” because they are frequently associated with dissatisfied employees. These factors are so frequently associated with dissatisfaction that Herzberg claims they never really provide satisfaction. When they’re present in sufficient quantities, we avoid dissatisfaction, but they do not contribute to satisfaction. Furthermore, since meeting these needs does not provide satisfaction, Herzberg concludes that they do not motivate workers.
Motivator factors involve our long-term need to pursue psychological growth (much like Maslow’s esteem and self-actualization needs). Motivators relate to job content. Job content is what we actually do when we perform our job duties. Herzberg considered job duties that lead to feelings of achievement and recognition to be motivators. He refers to these factors as “satisfiers” to reflect their ability to provide satisfying experiences. When these needs are met, we experience satisfaction. Because meeting these needs provides satisfaction, they motivate workers. More specifically, Herzberg believes these motivators lead to high performance (achievement), and the high performance itself leads to satisfaction.
The unique feature of Herzberg’s theory is that job conditions that prevent dissatisfaction do not cause satisfaction. Satisfaction and dissatisfaction are on different “scales” in his view. Hygienes can cause dissatisfaction if they are not present in sufficient levels. Thus, an employee can be dissatisfied with low pay. But paying him more will not cause long-term satisfaction unless motivators are present. Good pay by itself will only make the employee neutral toward work; to attain satisfaction, employees need challenging job duties that result in a sense of achievement. Employees can be dissatisfied, neutral, or satisfied with their jobs, depending on their levels of hygienes and motivators. Herzberg’s theory even allows for the possibility that an employee can be satisfied and dissatisfied at the same time—the “I love my job but I hate the pay” situation!
Herzberg’s theory has made lasting contributions to organizational research and managerial practice. Researchers have used it to identify the wide range of factors that influence worker reactions. Previously, most organizations attended primarily to hygiene factors. Because of Herzberg’s work, organizations today realize the potential of motivators. Job enrichment programs are among the many direct results of his research.
Herzberg’s work suggests a two-stage process for managing employee motivation and satisfaction. First, managers should address the hygiene factors. Intense forms of dissatisfaction distract employees from important work-related activities and tend to be demotivating. 16 Thus, managers should make sure that such basic needs as adequate pay, safe and clean working conditions, and opportunities for social interaction are met. They should then address the much more powerful motivator needs, in which workers experience recognition, responsibility, achievement, and growth. If motivator needs are ignored, neither long-term satisfaction nor high motivation is likely. When motivator needs are met, however, employees feel satisfied and are motivated to perform well.
Self-Determination Theory
One major implication of Herzberg’s motivator-hygiene theory is the somewhat counterintuitive idea that managers should focus more on motivators than on hygienes. (After all, doesn’t everyone want to be paid well? Organizations have held this out as a chief motivator for decades!) Why might concentrating on motivators give better results? To answer this question, we must examine types of motivation. Organizational behavior researchers often classify motivation in terms of what stimulates it. In the case of extrinsic motivation , we endeavor to acquire something that satisfies a lower-order need. Jobs that pay well and that are performed in safe, clean working conditions with adequate supervision and resources directly or indirectly satisfy these lower-order needs. These “outside the person” factors are extrinsic rewards .
Factors “inside” the person that cause people to perform tasks, intrinsic motivation , arise out of performing a task in and of itself because it is interesting or “fun” to do. The task is enjoyable, so we continue to do it even in the absence of extrinsic rewards. That is, we are motivated by intrinsic rewards, rewards that we more or less give ourselves. Intrinsic rewards satisfy higher-order needs like relatedness and growth in ERG theory. When we sense that we are valuable contributors, are achieving something important, or are getting better at some skill, we like this feeling and strive to maintain it.
Self-determination theory (SDT) seeks to explain not only what causes motivation, but also how extrinsic rewards affect intrinsic motivation. 17 In SDT, extrinsic motivation refers to the performance of an activity in order to attain some valued outcome, while intrinsic motivation refers to performing an activity for the inherent satisfaction of the activity itself. SDT specifies when an activity will be intrinsically motivating and when it will not. Considerable numbers of studies have demonstrated that tasks are intrinsically motivating when they satisfy at least one of three higher-order needs: competence, autonomy, and relatedness. These precepts from SDT are entirely consistent with earlier discussions of theories by McClelland, Maslow, Alderfer, and Herzberg.
SDT takes the concepts of extrinsic rewards and intrinsic motivation further than the other need theories. SDT researchers have consistently found that as the level of extrinsic rewards increases, the amount of intrinsic motivation decreases. That is, SDT posits that extrinsic rewards not only do not provide intrinsic motivation, they diminish it. Think of this in terms of hobbies. Some people like to knit, others like to carve wood. They do it because it is intrinsically motivating; the hobby satisfies needs for competence, autonomy, and relatedness. But what happens if these hobbyists start getting paid well for their sweaters and carvings? Over time the hobby becomes less fun and is done in order to receive extrinsic rewards (money). Extrinsic motivation increases as intrinsic motivation decreases! When extrinsic rewards are present, people do not feel like what they do builds competence, is self-determined, or enhances relationships with others.
SDT theory has interesting implications for the management of organizational behavior. Some jobs are by their very nature uninteresting and unlikely to be made interesting. Automation has eliminated many such jobs, but they are still numerous. SDT would suggest that the primary way to motivate high performance for such jobs is to make performance contingent on extrinsic rewards. Relatively high pay is necessary to sustain performance on certain low-skill jobs. On the other hand, SDT would suggest that to enhance intrinsic motivation on jobs that are interesting, don’t focus only on increasing extrinsic rewards (like large pay bonuses). Instead, create even more opportunities for employees to satisfy their needs for competence, autonomy, and relatedness. That means giving them opportunities to learn new skills, to perform their jobs without interference, and to develop meaningful relationships with other customers and employees in other departments. Such actions enhance intrinsic rewards.
You may have noticed that content theories are somewhat quiet about what determines the intensity of motivation. For example, some people steal to satisfy their lower-order needs (they have high intensity). But most of us don’t steal. Why is this? Process theories of motivation attempt to explain this aspect of motivation by focusing on the intensity of motivation as well as its direction. According to self-determination theory, skilled workers who are given a chance to hone their skills and the freedom to practice their craft will be intrinsically motivated.
Exercise \(\PageIndex{1}\)
- Understand the content theories of motivation.
- Understand the contributions that Murray, McClelland, Maslow, Alderfer, and Herzberg made toward an understanding of human motivation.


5.1: Introduction
Introduction
All rocks found on the Earth are classified into one of three groups: igneous, sedimentary, or metamorphic. This rock classification is based on the origin of each of these rock type or the rock-forming process that formed the rock. The focus of this chapter will be on igneous rocks, which are the only rocks that form from what was once a molten or liquid state. Therefore, based on their mode of origin, igneous rocks are defined as those rock types that form by the cooling of magma or lava. You would be right in thinking that there is more to the classification of igneous rocks than stated in the previous sentence, as there are dozens of different igneous rocks that are considered commonplace, dozens of more types that are less common, and also quite a few igneous rock types that are quite scarce. Yet each igneous rock has a name that distinguishes it from all the rest. So, if they all start out as molten material (magma or lava), which must harden to form a rock, then it is logical to assume that these igneous rocks differ from one another primarily due to:
- the original composition of the molten material from which the rock is derived, and
- the cooling process of the molten material that ended up forming the rock. These two parameters— composition and texture— define the classification of igneous rocks. Igneous rock composition refers to what is in the rock (the chemical composition or the minerals that are present), and a rocks’ texture refers to the features that we see in the rock, such as the mineral sizes or the presence of glass, fragmented material, or vesicles (holes) in the igneous rock.
In this module you will be learning about intrusive and extrusive igneous rocks. Igneous rocks are very commonly encountered in nature. Well-known examples are the basalt rocks of Hawaii that formed during volcanic eruptions on the islands. However, igneous rocks have formed throughout Earth’s history and, through the process of plate tectonics, are often located at great distances from active volcanoes. For example, in the Catalina Mountains to the north of Tucson, there are many examples of igneous rocks, including three sills of granite that formed about 50 million years ago through an intrusion into an older granite unit. In this module, you will learn about the different types of igneous deposits, including sills, and how composition is related to the environment in which the rocks formed.
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Module Objectives
At the completion of this module you will be able to:
- Explain the rock cycle and the processes involved.
- Name and describe the different types of intrusive and extrusive igneous deposits.
- Describe the composition of different types of igneous rocks and explain the processes involved in their formation.
- Explain which tectonic environment is associated with which kinds of igneous rock.
Activities Overview
See the Schedule of Work for dates of availability and due dates.
Be sure to read through the directions for all of this module’s activities before getting started so that you can plan your time accordingly. You are expected to work on this course throughout the week.
Read
Physical Geology by Steven Earle
- Chapter 3 (Intrusive Igneous Rocks)
Module 5 Assignment: Igneous Rock Lab
10 points
After you complete the reading, you can start working on Module 5 Assignment – Igneous Rock Lab.
Module 5 Quiz
10 points
Module 5 Quiz has 10 multiple-choice questions and is based on the content of the Module 5 readings and Assignment 5.
The quiz is worth a total of 10 points (1 points per question). You will have only 10 minutes to complete the quiz, and you may take this quiz only once. Note : that is not enough time to look up the answers!
Make sure that you fully understand all of the concepts presented and study for this quiz as though it were going to be proctored in a classroom, or you will likely find yourself running out of time.
Keep track of the time, and be sure to look over your full quiz results after you have submitted it for a grade.
Exam 1
75 points
Exam 1 is due this module. You will be asked to put your knowledge to work in the Great Outdoors or at your local rock shop! You will be assembling a mineral kit with 5 minerals of your choice, composed of samples you have collected yourself or purchased individually. As a result, your kit will be customized according to your own interests.
You can read more about this in the Exam 1 Instructions .
This is a “work-at-home” project. You will submit the results from your project in the Assignments tool.
Check the Course Schedule for due date.
Your Questions and Concerns…
Please contact me if you have any questions or concerns.
General course questions : If your question is of a general nature such that other students would benefit from the answer, then go to the discussions area and post it as a question thread in the “General course questions” discussion area.
Personal questions : If your question is personal, (e.g. regarding my comments to you specifically), then send me an email from within this course.


9.5: The United States and the Japanese War
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As Americans celebrated V-E (Victory in Europe) Day, they redirected their full attention to the still-raging Pacific War. As in Europe, the war in the Pacific started slowly. After Pearl Harbor, the American-controlled Philippine archipelago fell to Japan. After running out of ammunition and supplies, the garrison of American and Filipino soldiers surrendered. The prisoners were marched eighty miles to their prisoner-of-war camp without food, water, or rest. Ten thousand died on the Bataan Death March. 11
But as Americans mobilized their armed forces, the tide turned. In the summer of 1942, American naval victories at the Battle of the Coral Sea and the aircraft carrier duel at the Battle of Midway crippled Japan’s Pacific naval operations. To dislodge Japan’s hold over the Pacific, the U.S. military began island hopping: attacking island after island, bypassing the strongest but seizing those capable of holding airfields to continue pushing Japan out of the region. Combat was vicious. At Guadalcanal American soldiers saw Japanese soldiers launch suicidal charges rather than surrender. Many Japanese soldiers refused to be taken prisoner or to take prisoners themselves. Such tactics, coupled with American racial prejudice, turned the Pacific Theater into a more brutal and barbarous conflict than the European Theater. 12
Japanese defenders fought tenaciously. Few battles were as one-sided as the Battle of the Philippine Sea, or what the Americans called the Japanese counterattack, the Great Marianas Turkey Shoot. Japanese soldiers bled the Americans in their advance across the Pacific. At Iwo Jima, an eight-square-mile island of volcanic rock, seventeen thousand Japanese soldiers held the island against seventy thousand Marines for over a month. At the cost of nearly their entire force, they inflicted almost thirty thousand casualties before the island was lost.
By February 1945, American bombers were in range of the mainland. Bombers hit Japan’s industrial facilities but suffered high casualties. To spare bomber crews from dangerous daylight raids, and to achieve maximum effect against Japan’s wooden cities, many American bombers dropped incendiary weapons that created massive firestorms and wreaked havoc on Japanese cities. Over sixty Japanese cities were fire-bombed. American fire bombs killed one hundred thousand civilians in Tokyo in March 1945.
In June 1945, after eighty days of fighting and tens of thousands of casualties, the Americans captured the island of Okinawa. The mainland of Japan was open before them. It was a viable base from which to launch a full invasion of the Japanese homeland and end the war.
Estimates varied, but given the tenacity of Japanese soldiers fighting on islands far from their home, some officials estimated that an invasion of the Japanese mainland could cost half a million American casualties and perhaps millions of Japanese civilians. Historians debate the many motivations that ultimately drove the Americans to use atomic weapons against Japan, and many American officials criticized the decision, but these would be the numbers later cited by government leaders and military officials to justify their use. 13
Early in the war, fearing that the Germans might develop an atomic bomb, the U.S. government launched the Manhattan Project, a hugely expensive, ambitious program to harness atomic energy and create a single weapon capable of leveling entire cities. The Americans successfully exploded the world’s first nuclear device, Trinity, in New Mexico in July 1945. (Physicist J. Robert Oppenheimer, the director of the Los Alamos Laboratory, where the bomb was designed, later recalled that the event reminded him of Hindu scripture: “Now I am become death, the destroyer of worlds.”) Two more bombs—Fat Man and Little Boy—were built and detonated over two Japanese cities in August. Hiroshima was hit on August 6. Over one hundred thousand civilians were killed. Nagasaki followed on August 9. Perhaps eighty thousand civilians were killed.
Emperor Hirohito announced the surrender of Japan on August 15. On September 2, aboard the battleship USS Missouri , delegates from the Japanese government formally signed their surrender. World War II was finally over.