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?
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QUESTION: How does the train move?

So what is gravity? A typical definition of gravity is that it is a force. It causes an attraction between two masses. According to this definition, anything that has mass exerts a force. Any object exerts gravity on other objects. It does not matter how small it is, it has gravity. The more matter an object has, the more gravity it has. Your pencil has a tiny bit of gravity, but far too little to notice. What about a planet? It would have a lot of gravity. An objects gravity exerts a pull on other objects. Friction only occurs between objects that are touching. Gravity can act between objects that are not touching. In fact, gravity can act over very long distances. Where else can you feel gravity?
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QUESTION: What does an objects gravity cause it to do?

Enter the Shoguns: Japan's austere, ruthless, but statesmanlike new ruler, Yoritomo Minamoto, set up his government in Kamakura (just south of modern Tokyo), well away from the "softening" influence of court life that had been the undoing of his predecessor, Kiyomori. First of the national rulers to take the title of sei-i tai-shogun ("barbarian-subduing great general"), Minamoto expanded and consolidated his power by confiscating lands from some of the defeated Taira and redistributing them to his samurai vassals. Minamoto died in 1199, and the feudal structure passed intact to the tutelage of his widow's family, the Hojo, who were content to play regent to a figurehead shogun, in much the same way as the Fujiwara had done with the emperor. The fiction of Japanese imperial power had become infinitely extendable. The emperor at Kyotostill seconded by a Fujiwara regent at courtlegitimized a Minamoto who was himself a military dictator controlled by a Hojo regent. In a country where form and substance were inextricably interrelated, two things counted in politics: symbolic authority and real power. Neither could exist without the other. A thwarted Mongol invasion in 1274 weakened the Kamakura regime. The fighting brought none of the usual spoils of war that provincial warlords and samurai had come to expect as payment. And the treasury was empty after earthquake, famine, and plague had crippled the economy. Buddhist monasteries were using their private armies to support imperial ambitions to bring power back to Kyoto. Worst of all, the Kamakura warriors, resenting the way the Kyoto court referred to them as "Eastern barbarians," sought refinement in a ruinous taste for luxury: extravagant feasts, rich costumes, and opulent homes. Kamakura was falling apart.
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QUESTION: How did Minamoto expand his power?

(CNN) -- Guatemala's government has declared a state of siege and sent hundreds of troops to a northern province where officials say a Mexican drug gang is overtaking towns and threatening residents. President Alvaro Colom announced the 30-day emergency rule in Alta Verapaz on Sunday. The rule allows the military to order anyone suspected of conspiring against the government to be arrested and imprisoned without a warrant, the state-run AGN news agency said. "Starting today, combined forces will retake the streets of Alta Verapaz," a government statement released Sunday morning said. Government data shows cells of the drug gang known as Los Zetas are in the area to protect drug trafficking paths between Honduras and Mexico, "intimidating the population with their heavy weapons and threatening farmers to give up their land for criminal activities," AGN reported. The state of siege also allows the government to place greater restrictions on public gatherings, travel visas and gun licenses, among other things, according to AGN. "The population should be calm. What we are doing is not intended to persecute honest, working people," Interior Minister Carlos Menocal told reporters. Menocal said operations in the coming days would aim to boost regional security, regain control of territory, identify criminal gangs and capture their members. In an interview with CNN en Espanol last month, Menocal said his country needed more help from the United States to combat cartels, which were increasingly carving out new drug transport paths. "In the end, the large majority of drugs travel through Central America, and the assignment of resources or the financial support of the United States government is not the same as Colombia and Mexico receive," he said. Menocal said clashes between authorities and Los Zetas had notably increased.
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QUESTION:
From whom, will the combined forces be retaking the streets of Alta Verapaz?