Take a look at this train in Figure 1.11. It looks very futuristic. What do you notice about it? Did you notice that the train has no wheels? How can a train have no wheels? It doesn't need wheels. It actually floats, or levitates, just above the track. Magnets enable the train to do this. This is not a normal train. This is a maglev train. The word maglev stands for magnetic levitation. Because it has no wheels, there is no friction. Some magnets hold the train up. Other magnets are used to move the train forward. This train can go very fast. It can reach speeds up to 480 kilometers (300 miles) per hour! Magnets are pretty cool. What exactly is a magnet? How is it able to exert such force?

Question: "How do magnets work to keep a maglev train moving?"

OPTIONS:
- no
- yes

Answer: "They give off waves of energy"

Response: no

He repeatedly calls on his followers to embrace martyrdom since "The walls of oppression and humiliation cannot be demolished except in a rain of bullets." For those yearning for a lost sense of order in an older, more tranquil world, he offers his "Caliphate" as an imagined alternative to today's uncertainty. For others, he offers simplistic conspiracies to explain their world. Bin Laden also relies heavily on the Egyptian writer Sayyid Qutb. A member of the Muslim Brotherhood executed in 1966 on charges of attempting to overthrow the government, Qutb mixed Islamic scholarship with a very superficial acquaintance with Western history and thought. Sent by the Egyptian government to study in the United States in the late 1940s, Qutb returned with an enormous loathing of Western society and history. He dismissed Western achievements as entirely material, arguing that Western society possesses "nothing that will satisfy its own conscience and justify its existence." Three basic themes emerge from Qutb's writings. First, he claimed that the world was beset with barbarism, licentiousness, and unbelief (a condition he called jahiliyya, the religious term for the period of ignorance prior to the revelations given to the Prophet Mohammed). Qutb argued that humans can choose only between Islam and jahiliyya. Second, he warned that more people, including Muslims, were attracted to jahiliyya and its material comforts than to his view of Islam; jahiliyya could therefore triumph over Islam. Third, no middle ground exists in what Qutb conceived as a struggle between God and Satan. All Muslims-as he defined them-therefore must take up arms in this fight. Any Muslim who rejects his ideas is just one more nonbeliever worthy of destruction. Bin Laden shares Qutb's stark view, permitting him and his followers to rationalize even unprovoked mass murder as righteous defense of an embattled faith. Many Americans have wondered, "Why do 'they' hate us?" Some also ask, "What can we do to stop these attacks?" Bin Laden and al Qaeda have given answers to both these questions.

Question: "Approximately how long after studying in the United States was Sayyid Qutb executed?"

OPTIONS:
- no
- yes

Answer: "16 years"

Response: no

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?"

OPTIONS:
- no
- yes

Answer: "turned the watch off"

Response: no

The mighty fane, with its three massive towers, rises majestically over the red roofs of the town. Its most striking feature is the great Norman screen, running up without buttresses or projections to the parapet and hiding the bases of the square, richly decorated towers of the west front. The plain centre of the screen is the work of Remigius, the first bishop. The rest of it is relieved with rich arcading of Late Norman and Early English periods. The wooden spires which crowned the towers were removed in 1807. In 1192 Hugh of Avalon determined to rebuild the Norman building of Remigius, which an earthquake had shaken. To him we owe the choir and eastern transept. His successors completed the western transept and began the west end of the nave. So much money had to be spent in rebuilding the central tower, which fell in 1239, that the canons could not rebuild the nave entirely, but had to incorporate the Norman end by Remigius. Unfortunately the axis of the west front does not correspond to that of the nave, which is too wide for its height. The low vaulting is a serious defect in the choir built by St. Hugh, but of the superb beauty of the Angel Choir, which encloses his shrine, there can be no doubt. In its richness of sculpture it is one of the masterpieces of Gothic architecture in England. The interior of the cathedral is remarkable for the harmony of its style, which is Lancet-Gothic, and the dim lighting of the nave only adds to its impressiveness.

Question: "What was so much money spent on building that the Cano could not rebuild the nave entirely?"

OPTIONS:
- no
- yes

Answer: "Money had to be spent in rebuilding the central tower, which fell in 1239"

Response:
yes