Sound waves are mechanical waves. They can travel only through matter. They cannot travel through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air out of the jar. The clock was still running, but the ticking could not be heard. Thats because the sound couldnt travel without air particles to transfer the sound energy. Is there any other place where sound cannot be heard? Here is a hint: is there any other place that does not have air molecules? Thats right, in space sound cannot be transferred. So can astronauts hear each other? Yes, they can, because they are in enclosed space stations or pressurized suits.In both cases, they are surrounded by air molecules. If they left their space ship and did not use their electronics, they would not be able to hear each other. Next time you watch a science fiction movie, think about this factoid. When spaceships are destroyed by hostile alien beings, there would be no sound heard. Sound waves can travel through many kinds of matter. 

Question: "In Boyle's experiment, what did he do to make the clock stop being heard while in the jar?"

Response: "turned the watch off"

A: no


To protect its seagoing interests and trade routes, Portugal established strategic garrisons in Goa (India), Malacca (East Indies), and Hormuz in the Persian Gulf. Portuguese explorers then embarked upon Macau (now Macao), the Congo, and various other parts of Africa, including the Sudan. The Portuguese policy was to avoid armed strife and to develop a trade empire, rather than to conquer nations. To this end it succeeded with relatively few blood-soaked episodes in its colonial history. Adventures abroad, however, proved disastrous during the second half of the 16th century. In 1557 the 14-year-old boy-king Sebastião ascended the throne, the beginning of a calamitous reign that was to end at the battle of Alcacer-Quiber (Morocco) in pursuit of a vain crusade. Sebastião's untimely demise, alongside some 18,000 ill-prepared, badly led followers, set the stage for a crisis of succession. For many years afterwards, legends and rumors bizarrely insisted that the king was still alive, and imposters turned up from time to time claiming the throne; those who were plausible enough to be deemed a threat were summarily executed. In fact, the only rightful claimant to the crown was the elderly Prince Henry. But after two years of alternating between the throne and his sickbed, he died, heirless. Surveying the situation and smelling an opportunity, Spain occupied the power vacuum, and Portugal's neighbor and long-time antagonist became its master. Spanish rule dictated Portugal's inadvertent involvement in Spain's ongoing wars. In 1587 a squadron of British ships commanded by Francis Drake attacked the Algarve (now a "legitimate target" as Spanish territory) and sacked Sagres, thus depriving the world of the relics of Henry the Navigator. Nine years later Faro was torched. The 1386 Treaty of Windsor, by which Britain and Portugal had pledged eternal friendship, seemed a distant memory. Portugal's empire was gradually eroded, and many of its trading posts (with the notable exception of Brazil) were picked off by the British and Dutch. Finally, after 60 years of Spanish rule, Portuguese noblemen (aided by the French, then at war with Spain) organized a palace coup and restored independence. The Great Disaster Portugal's greatest misfortune struck on All Saint's Day, 1 November 1755. 

Question: "What created a crisis of succession following this era of increased trade?"

Response: "They conquered Congo"

A: no


Charlie Y. Reader is a 35-year-old theatrical agent in New York , living a seemingly idyllic life as a bachelor . Numerous women ( among them Poppy , Helen , and Jessica come and go , cleaning and cooking for him . Charlie 's best friend since kindergarten , Joe McCall , who has a wife named Ethel and children in Indianapolis , comes to New York for a stay at Charlie 's apartment , claiming that the excitement is gone from his 11-year marriage and that he wants to leave his wife . Joe envies and is amazed by Charlie 's parade of girlfriends , while Charlie professes admiration for Joe 's married life and family . At an audition , Charlie meets singer-actress Julie Gillis . She has her life planned to a tight schedule , determined to marry and retire from performing to a life of child-rearing by 22 . Although at first she wards off Charlie 's advances , she comes to see him as the ideal man for her plans . Julie demands that Charlie stop seeing other women . Charlie balks , but he begins to fall in love with her . Joe starts keeping company with Sylvia Crewes , a sophisticated classical musician and a typically neglected lover of Charlie 's . Sylvia is approaching 33 and desires marriage as much as the younger Julie does . One day , annoyed by Julie and possibly jealous of Joe 's attentions , Charlie blurts out a proposal of marriage to Sylvia . She is thrilled , only to discover the morning after their engagement party that he has proposed to Julie as well . Joe confesses his love to Sylvia and asks her to marry him . 

Question: "How old is Joe McCall's best friend?"

Response: "22"

A:
no