home work 6

home work 6 - It would violate the second law in...

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Home Work # 6 Chapter 8 Exercises 2. If you open the door of your refrigerator with the hope of cooling your room, you will find that the room’s temperature actually increases somewhat. Why doesn’t the refrigerator remove heat from the room? When we open the refrigerator we only move thermanl energy or the heat from on section in the room to another, also more thermal energy is produced. 4. If you block the outlet of a hand bicycle pump and push the handle inward to compress the air inside the pump, the pump will become warmer. Why? When we push down on the handle we are doing work that is converted into thermal energy thus making the pump warmer. 12. Suppose someone claimed to have a device that could convert heat from the room into electric power continuously. You would know that this device was a fraud because it would violate the second law of thermodynamics. Explain.
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Unformatted text preview: It would violate the second law in thermodynamics because it would produce a decrease in entropy to convert thermal into electrical energy. 14. If you transfer a glass baking dish from a hot oven to a cold basin of water, that dish will probably shatter. What produces the ordered mechanical energy needed to tear the glass apart? Heat turns into mechanical work thanks to entropy when the hot glass touches the water thus making it shatter. Problems 6. An ideally efficient freezer cools food to 260 K. If room temperature is 300 K, how much work does this freezer consume when removing 100 J of heat from the food? W = (100 J)300 K 260 K / (260 K) = 15.4 J 7. An ideally efficient refrigerator removes 900 J of heat from food at 270 K. How much heat does it then deliver to the 300 K room air? W = (900 J)(300 K 270 K) / (270 K) = 100 J 100 J + 900 J = 1000 J...
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