Question:
What if two children push a swing at the same time? Would the swing go higher? Yes, together their force would be more. It is common for forces to be combined. Most objects on Earth have at least two forces acting on them. Do you know what one of them is? Of course, that force is gravity. How many forces do you have on you right now? Gravity pulls you down toward the center of Earth. Your legs exert a downward force. They hold you up against the pull of gravity. Consider the example in Figure 1.3. A book is resting on a table. Gravity pulls the book downward. It has a force of 20 newtons. At the same time, the table pushes the book upward. Its force is also 20 newtons. The table opposes the pull of gravity. After reading the above, is "There is more force acting on the swing" the correct answer to the question "Why would a swing go higher when two children push it at the same time?"?

Answer:
yes

Question:
Bin Laden and his aides did not need a very large sum to finance their planned attack on America. The 9/11 plotters eventually spent somewhere between $400,000 and $500,000 to plan and conduct their attack. Consistent with the importance of the project, al Qaeda funded the plotters. KSM provided his operatives with nearly all the money they needed to travel to the United States, train, and live. The plotters' tradecraft was not especially sophisticated, but it was good enough. They moved, stored, and spent their money in ordinary ways, easily defeating the detection mechanisms in place at the time. The origin of the funds remains unknown, although we have a general idea of how al Qaeda financed itself during the period leading up to 9/11. General Financing As we explained in chapter 2, Bin Laden did not fund al Qaeda through a personal fortune and a network of businesses in Sudan. Instead, al Qaeda relied primarily on a fund-raising network developed over time. The CIA now estimates that it cost al Qaeda about $30 million per year to sustain its activities before 9/11 and that this money was raised almost entirely through donations. For many years, the United States thought Bin Laden financed al Qaeda's expenses through a vast personal inheritance. Bin Laden purportedly inherited approximately $300 million when his father died, and was rumored to have had access to these funds to wage jihad while in Sudan and Afghanistan and to secure his leadership position in al Qaeda. In early 2000, the U.S. government discovered a different reality: roughly from 1970 through 1994, Bin Laden received about $1 million per year-a significant sum, to be sure, but not a $300 million fortune that could be used to fund jihad. Then, as part of a Saudi government crackdown early in the 1990s, the Bin Laden family was forced to find a buyer for Usama's share of the family company in 1994. The Saudi government subsequently froze the proceeds of the sale. This action had the effect of divesting Bin Laden of what otherwise might indeed have been a large fortune. Nor were Bin Laden's assets in Sudan a source of money for al Qaeda. When Bin Laden lived in Sudan from 1991 to 1996, he owned a number of businesses and other assets. After reading the above, is "Donations" the correct answer to the question "How did Bin Laden fund the attack against America?"?

Answer:
yes

Question:
The Glory of Melaka: In the early days, if you were not a pirate or a mosquito, Melaka was not much of a place to live. The land was infertile, just a swampy plain, the river small and sluggish. But it had a sheltered harbor, protected from the monsoons by neighboring Sumatra. Later, the strategic location and deep-water channel close to the coast brought in the bigger vessels of the trade-wind traffic crossing the Indian Ocean. The first to realize the larger commercial potential, as so often throughout the country's subsequent history, were the Chinese. In 1409, under a new directive from Emperor Chu Ti to pursue trade in the South Seas and the Indian Ocean, a Chinese fleet of 50 ships headed by Admiral Cheng Ho called in at Melaka. They made Parameswara an offer he could not refuse: port facilities and an annual financial tribute in exchange for Chinese protection against the marauding Thais. In 1411, Parameswara took the money to Beijing himself, and the emperor gratefully made him a vassal king. Twenty years later, the Chinese withdrew again from the South Seas trade. The new ruler of Melaka, Sri Maharajah, switched his allegiance to the Muslim trading fraternity by marrying into the Muslim faith, wedding the daughter of a sultan in Sumatra. Islam won its place in Malaya not by conquestas had been the case in North Africa and Europebut by trade, dynastic alliances, and peaceful preaching. Bengali peddlers had already brought the faith to the east coast. In Melaka and throughout the peninsula, Islam thrived as a strong, male-dominated religion of individuality, offering dynamic leadership and preaching brotherhood and self-relianceall qualities ideally suited to the coastal trade. At the same time, Sufi mystics synthesized Islamic teaching with local Malay traditions of animistic magic and charisma, though Islam did not become the state religion until Muzaffar Shah became sultan of Melaka (14461459). But the key figure in the sultanate was Tun Perak, bendahara (prime minister) and military commander. He expanded Melaka's power along the west coast and down to Singapore and the neighboring Bintan islands. He also had orang laut pirates patrolling the seas to extort tribute from passing ships. After Ailied district chiefs had repelled assaults from Thai-controlled armies from Pahang, Tun Perak personally led a famous victory over a Thai fleet off Batu Pahat in 1456. After reading the above, is "Married a sultan in Sumatra" the correct answer to the question "What did Sri Maharajah do that contributed to Islam winning its place in Malaya?"?

Answer:
yes

Question:
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? After reading the above, is "Air pressure" the correct answer to the question "What holds the train up and moves it forward?"?

Answer:
no