Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Ex Input:
Force is defined as a push or a pull acting on an object. Examples of forces include friction and gravity. Both are covered in detail later in this chapter. Another example of force is applied force. It occurs when a person or thing applies force to an object, like the girl pushing the swing in Figure 13.1. The force of the push causes the swing to move. Force is a vector because it has both size and direction. For example, the girl in Figure 13.1 is pushing the swing away from herself. Thats the direction of the force. She can give the swing a strong push or a weak push. Thats the size, or strength, of the force. Like other vectors, forces can be represented with arrows. Figure 13.2 shows some examples. The length of each arrow represents the strength of the force, and the way the arrow points represents the direction of the force. How could you use an arrow to represent the girls push on the swing in Figure 13.1? The SI unit of force is the newton (N). One newton is the amount of force that causes a mass of 1 kilogram to accelerate at 1 m/s2 . Thus, the newton can also be expressed as kgm/s2 . The newton was named for the scientist Sir Isaac Newton, who is famous for his law of gravity. Youll learn more about Sir Isaac Newton later in the chapter. More than one force may act on an object at the same time. In fact, just about all objects on Earth have at least two forces acting on them at all times. One force is gravity, which pulls objects down toward the center of Earth. The other force is an upward force that may be provided by the ground or other surface. Consider the example in Figure 13.3. A book is resting on a table. Gravity pulls the book downward with a force of 20 newtons. At the same time, the table pushes the book upward with a force of 20 newtons. The combined forces acting on the book or any other object are called the net force. This is the overall force acting on an object that takes into account all of the individual forces acting on the object. You can learn more about the concept of net force at this URL: . When two forces act on an object in opposite directions, like the book on the table, the net force is equal to the difference between the two forces. In other words, one force is subtracted from the other to calculate the net force. If the opposing forces are equal in strength, the net force is zero. Thats what happens with the book on the table. The upward force minus the downward force equals zero (20 N up - 20 N down = 0 N). Because the forces on the book are balanced, the book remains on the table and doesnt move. In addition to these downward and upward forces, which generally cancel each other out, forces may push or pull an object in other directions. Look at the dogs playing tug-of-war in Figure 13.4. One dog is pulling on the rope with a force of 10 newtons to the left. The other dog is pulling on the rope with a force of 12 newtons to the right. These opposing forces are not equal in strength, so they are unbalanced. When opposing forces are unbalanced, the net force is greater than zero. The net force on the rope is 2 newtons to the right, so the rope will move to the right. Two forces may act on an object in the same direction. You can see an example of this in Figure 13.5. After the man on the left lifts up the couch, he will push the couch to the right with a force of 25 newtons. At the same time, the man to the right is pulling the couch to the right with a force of 20 newtons. When two forces act in the same direction, the net force is equal to the sum of the forces. This always results in a stronger force than either of the individual forces

Ex Output:
force that a person or thing exerts on to an object

Ex Input:
The film starts on June 16, 1994 with Jesse meeting Celine on a train from Budapest and striking up a conversation with her. Jesse is going to Vienna to catch a flight back to the United States, whereas Celine is returning to university in Paris after visiting her grandmother. When they reach Vienna, Jesse convinces Celine to disembark with him, saying that 10 or 20 years down the road, she might not be happy with her marriage and might wonder how her life would have been different if she had picked another guy, and this is a chance to realize that he himself is not that different from the rest; in his words, he is "the same boring, unmotivated guy." Jesse has to catch a flight early in the morning and does not have enough money to rent a room for the night, so they decide to roam around in Vienna. After visiting a few landmarks in Vienna, they share a kiss at the top of the Wiener Riesenrad at sunset and start to feel a romantic connection. As they continue to roam around the city, they begin to talk more openly with each other, with conversations ranging from topics about love, life, religion, and their observations of the city. Celine tells Jesse that her last boyfriend broke up with her six months ago, claiming that she "loved him too much". When questioned, Jesse reveals he had initially come to Europe to spend time with his girlfriend who was studying in Madrid, but they had broken up when she was avoiding him while he was there. He decided to take a cheap flight home, via Vienna, but it did not leave for two weeks so he bought a Eurail pass and traveled around Europe. When they are walking alongside the Donaukanal (Danube canal) they are approached by a man who, instead of begging, offers to write them a poem with a word of their choice in it. Jesse and Celine decide on the word "milkshake", and are soon presented with the poem Delusion Angel (written for the film by the poet David Jewell). In a traditional Viennese cafe, Jesse and Celine stage fake phone conversations with each other, playing each other's friends they pretend to call. Celine reveals that she was ready to get off the train with Jesse before he convinced her. Jesse reveals that after he broke up with his girlfriend, he bought a flight that really was not much cheaper, and all he really wanted was an escape from his life. They admit their attraction to each other and how the night has made them feel, though they understand that they probably will not see each other again when they leave. They simply decide to make the best of what time they have left, ending the night with the implication of a sexual encounter between them. At that point, Jesse explains that if given the choice, he would marry her instead of never seeing her again. The film ends the next day at the train station, where, just as Celine's train is about to leave, the couple decides not to exchange any contact information but instead to meet at the same place in six months.

Ex Output:
Strangers on a train, Jesse convinces Cline to disembark with him in what city?

Ex Input:
Something that is elastic can return to its original shape after being stretched or compressed. This property is called elasticity. As you stretch or compress an elastic material, it resists the change in shape. It exerts a counter force in the opposite direction. This force is called elastic force. Elastic force causes the material to spring back to its original shape as soon as the stretching or compressing force is released. You can watch a demonstration of elastic force at this URL: (3:57). MEDIA Click image to the left or use the URL below. URL: Elastic force can be very useful. You probably use it yourself every day. A few common uses of elastic force are pictured in Figure 13.25. Did you ever use a resistance band like the one in the figure? When you pull on the band, it stretches but doesnt break. The resistance you feel when you pull on it is elastic force. The resistance of the band to stretching is what gives your muscles a workout. After you stop pulling on the band, it returns to its original shape, ready for the next workout. Springs like the ones in Figure 13.26 also have elastic force when they are stretched or compressed. And like stretchy materials, they return to their original shape when the stretching or compressing force is released. Because of these properties, springs are used in scales to measure weight. They also cushion the ride in a car and provide springy support beneath a mattress. Can you think of other uses of springs?

Ex Output:
structure that returns to its original shape after being stretched or compressed