If you push against the desk and it does not move, then you have not done any work on the desk because the desk has not moved. In science, work is force applied through a distance. Have you done any work on the desk? The answer is no, no matter how tired you get from the effort. Motion and work Press your hand against the surface of your desk as hard as you can. However, in science, the word work is used in a different way. The word work might also mean exerting a force with muscles. In that sense, work can be anything from fixing cars to designing Web sites. To many people, the word work means something that people do to earn money. As the gas heats the room, it cools and changes back to a liquid and enters the expansion valve again. Because the gas is warmer than the room, thermal energy spreads from the gas to the room. The warm gas is pumped through the condenser coils. This makes the gas warmer than the temperature of the room. The gas then is pumped to a compressor that does work on the gas by compressing it. When this happens, the inside of the refrigerator cools. The cold gas is pumped through pipes inside the refrigerator, where it absorbs thermal energy from the area where you keep your food. As a result, the coolant transfers energy to its surroundings and the coolant cools. This means that the coolant does work on its surroundings. When the coolant expands as it changes into a gas, it pushes outward on its surroundings. Liquid coolant is pumped through an expansion valve and changes into a gas. Figure 20 shows how a refrigerator operates. A refrigerator makes the room that it is in warmer. The energy to do the work comes from the electrical energy the refrigerator obtains from an electrical outlet. Refrigerators A refrigerator does work as it transfers thermal energy from inside the cool refrigerator to the warmer room.
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