Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: A machine is any device that makes work easier by changing a force. When you use a machine, you apply force to the machine. This force is called the input force. The machine, in turn, applies force to an object. This force is called the output force. Recall that work equals force multiplied by distance: Work = Force Distance The force you apply to a machine is applied over a given distance, called the input distance. The force applied by the machine to the object is also applied over a distance, called the output distance. The output distance may or may not be the same as the input distance. Machines make work easier by increasing the amount of force that is applied, increasing the distance over which the force is applied, or changing the direction in which the force is applied. Contrary to popular belief, machines do not increase the amount of work that is done. They just change how the work is done. So if a machine increases the force applied, it must apply the force over a shorter distance. Similarly, if a machine increases the distance over which the force is applied, it must apply less force. Examples of machines that increase force are doorknobs and nutcrackers. Figure 16.8 explains how these machines work. In each case, the force applied by the user is less than the force applied by the machine, but the machine applies the force over a shorter distance. Examples of machines that increase the distance over which force is applied are paddles and hammers. Figure 16.9 explains how these machines work. In each case, the machine increases the distance over which the force is applied, but it reduces the strength of the applied force. Some machines change the direction of the force applied by the user. They may or may not also change the strength of the force or the distance over which it is applied. Two examples of machines that work in this way are claw hammers and the rope systems (pulleys) that raise or lower flags on flagpoles. Figure 16.10 explains how these machines work. In each case, the direction of the force applied by the user is reversed by the machine. How does this make it easier to do the job? An exoskeleton suit may seem like science fiction, turning ordinary humans into super heroes. But wearable robots are moving forward into reality. And for paraplegics, the ability to stand and walk that these machines provide is a super power. QUEST meets Austin Whitney and Tamara Mena, two "Exoskeleton Test Pilots" who are now putting this new technology through its paces. For more information on exoskeleton suits, see [Link] MEDIA Click image to the left or use the URL below. URL: You read above that machines do not increase the work done on an object. In other words, you cant get more work out of a machine than you put into it. In fact, machines always do less work on the object than the user does on the machine. Thats because all machines must use some of the work put into them to overcome friction. How much work? It depends on the efficiency of the machine. Efficiency is the percent of input work that becomes output work. It is a measure of how well a machine reduces friction. Consider the ramp in Figure 16.11. Its easier to push the heavy piece of furniture up the ramp to the truck than to lift it straight up off the ground. However, pushing the furniture over the surface of the ramp creates a lot of friction. Some of the force applied to moving the furniture must be used to overcome the friction. It would be more efficient to use a dolly on wheels to roll the furniture up the ramp. Thats because rolling friction is much less than sliding friction. As a result, the efficiency of the ramp would be greater with a dolly. Efficiency can be calculated with the equation: Efficiency = Output work 100% Input work Consider a machine that puts out 6000 joules of work. To produce that much work from the machine requires the user to put in 8000 joules of work. To find the efficiency of the machine, 
 Question: force applied by a machine
Example Output: output force

Example Input: Context: Below are Top 10 Scholarly Stars in America in 2011. It's not always about fame and fortune for these celebs - education is a priority in their lives. Find out what scholarly stars have earned degrees and diplomas or are returning to the classroom as you head back to school. No. 10: James Franco James has attended FOUR prestigious universities in his life: UCLA, New York University, Columbia University and Yale University. We hear he's is so serious about school, he missed the Oscar nominations to attend class! No. 9: Natalie Portman Natalie Portman is so Ivy League: she graduated from Harvard University in 2003, thanks to her parents, who she says always made sure she put her studies before her acting. No. 8: Haley Joel Osment When students at NYU heard Haley Joel would be joining them as a freshman in 2006, they chalked the campus' sidewalks with his famous Sixth Sense movie line: "I see dead people." No. 7: Emma Watson Although Emma Watson put her education on hold to wrap up the Harry Potter film series, in July 2011 she announced that she was going back to school at Brown University to complete her degree. No. 6: Dakota and Elle Fanning Celeb sisters Dakota and Elle Fanning are stars on screen and in class. Dakota was her high school's homecoming queen two years in a row while Elle, who still attends middle school, somehow manages to balance her acting career with math tests and gym class. No. 5: Mara Wilson Mara Wilson graduated from NYU in 2009. Mara, who played the adorable Nattie in Mrs. Doubtfire, eventually grew up and headed to New York to attend NYU's Tisch School of the Arts; she graduated in 2009. No. 4: Tyra Banks Tyra Banks is known for being a savvy businesswoman, but even the best could use some formal training. She enrolled in Harvard Business School in 2011 and even went so far as to live in a dorm with her fellow classmates! "We live in dorms," confirmed the TV star. "I have my own room but we share a kitchen, living room and study area. It's mandatory dorms. I freaked out. In the beginning I was like, 'Oh yes, I'm going to Harvard and I'll be at the Four Seasons down the street.' And they were like, 'Girl, you're living in dorms!'" No. 3: Shakira Singer Shakira is resting her hips and giving her brain a workout at UCLA, attending classes on the history of western civilization so she could "learn from the best". No. 2: Steven Spielberg Director Steven skipped getting a formal education to be an unpaid intern at Universal Studios, where he learned his tricks of the _ . But eventually he did go back and earned his film degree in 2002. No. 1: Danica McKellar Danica McKellar is a math whiz. She used to be known for starring as Winnie Cooper in the Wonder Years, but Danica is also a UCLA graduate, math whiz and education advocate who's written three best-selling books encouraging middle-school girls to have confidence and succeed in mathematics. 
 Question: How many stars referred to in the material studied or will go to UCLA?
Example Output: three.

Example Input: Context: In 1851, a French scientist named Lon Foucault took an iron sphere and hung it from a wire. He pulled the sphere to one side and then released it, as a pendulum. Although a pendulum set in motion should not change its motion, Foucault observed that his pendulum did seem to change direction relative to the circle below. Foucault concluded that Earth was moving underneath the pendulum. People at that time already knew that Earth rotated on its axis, but Foucaults experiment was nice confirmation. Imagine a line passing through the center of Earth that goes through both the North Pole and the South Pole. This imaginary line is called an axis. Earth spins around its axis, just as a top spins around its spindle. This spinning movement is called Earths rotation. An observer in space will see that Earth requires 23 hours, 59 minutes, and 4 seconds to make one complete rotation on its axis. But because Earth moves around the Sun at the same time that it is rotating, the planet must turn just a little bit more to reach the same place relative to the Sun. Hence the length of a day on Earth is actually 24 hours. At the Equator, the Earth rotates at a speed of about 1,700 km per hour, but at the poles the movement speed is nearly nothing. Earth rotates once on its axis about every 24 hours. To an observer looking down at the North Pole, the rotation appears counterclockwise. From nearly all points on Earth, the Sun appears to move across the sky from east to west each day. Of course, the Sun is not moving from east to west at all; Earth is rotating. The Moon and stars also seem to rise in the east and set in the west. Earths rotation means that there is a cycle of daylight and darkness approximately every 24 hours, the length of a day. Different places experience sunset and sunrise at different times and the amount of daylight and darkness also differs by location. Shadows are areas where an object obstructs a light source so that darkness takes on the form of the object. On Earth, a shadow can be cast by the Sun, Moon, or (rarely) Mercury or Venus. Click image to the left or use the URL below. URL: 
 Question: a pendulum in paris confirmed the existence of
Example Output:
earths rotation.