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.

[EX Q]: 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
[EX A]: output force

[EX Q]: Context: After the defeat of several Song armies in the north, Emperor Qinzong wanted to negotiate a truce with the Jin, but he committed a massive strategic blunder when he commanded his remaining armies to protect prefectural cities instead of Kaifeng. Neglecting the importance of the capital, he left Kaifeng defended with fewer than 100,000 soldiers. The Song forces were dispersed throughout China, powerless to stop the second Jurchen siege of the city. The Jin assault commenced in mid December 1126. Even as fighting raged on, Qinzong continued to sue for peace, but Jin demands for territory were enormous: they wanted all provinces north of the Yellow River. After more than twenty days of heavy combat against the besieging forces, Song defenses were decimated and the morale of Song soldiers was on the decline. On January 9, 1127, the Jurchens broke through and started to loot the conquered city. Emperor Qinzong tried to appease the victors by offering the remaining wealth of the capital. The royal treasury was emptied and the belongings of the city's residents were seized. The Song emperor offered his unconditional surrender a few days later. Qinzong, the former emperor Huizong, and members of the Song court were captured by the Jurchens as hostages. They were taken north to Huining , where they were stripped of their royal privileges and reduced to commoners. The former emperors were humiliated by their captors. They were mocked with disparaging titles like "Muddled Virtue" and "Double Muddled". In 1128 the Jin made them perform a ritual meant for war criminals. The harsh treatment of the Song royalty softened after the death of Huizong in 1135. Titles were granted to the deceased monarch, and his son Qinzong was promoted to Duke, a position with a salary. 
 Question: Which happened first, the seizing of the resident's belongings to give to the Jin, or unconditional surrender of the Song emperor?
[EX A]: belongings of the city's residents

[EX Q]: Context: Melissa and Roman McCoy were looking forward to the Christmas. But on December 5th, Roman got a phone call that changed everything. Melissa had been in a terrible car accident, and the doctor had little hope she would make it. "He said the next six to eight hours were critical in determining whether she would live or not. And I just wept," Roman said. "A lot of pressure built up inside, and I just dropped my cell phone on the ground when I heard that. It was the worst feeling that I've ever felt." Melissa, a college English professor, was on her way to class when her car hit into a mound of dirt and rolled over several times. Roman recalled, "I could only think how I am going to raise my kids without their mother. If she did live, how would I take care of her and my kids? The questions you never want to ask yourself, I had to face." Melissa survived the first night. She had injuries to her stomach and lungs and worse, she suffered severe injuries to her brain. She didn't recognize anyone, even her own husband. "Over the next few days, she remained unresponsive to treatments. The brain surgeon never really gave us much hope." Days passed and Melissa didn't improve. Christmas Eve, Roman was by her side in the hospital. Then, he received a Christmas gift he would never forget. "That evening, she woke up and was just as clear as before, recognized everybody, and was able to read. It was just amazing. I saw her bright smile and her sense of humor. The only way I could describe it is that the weight of the darkness that had hovered over me was just completely gone." Melissa quickly improved, and she is back to being a wife, mom, and professor. There is no sign of damage from the brain. Melissa said, "I thank him for everything now. It's not just 'thank you for my job, thank you for my children.' It's 'thank you for every aspect of my life.'" 
 Question: The worst injuries that Melissa had were to her .
[EX A]:
brain