[Toupadakis] 09WINTER - WQ Problem

[Toupadakis] 09WINTER - WQ Problem - 7 Your hands(A get...

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TOUPADAKIS © AT WINTER2009 Problem (By definition energy is transferred as heat or as work) Consider the energy transfer processes between a system A and a system B below.  For each case,  answer if the energy is transferred as heat or work.  1. The sun (A) heats up the seat (B) of your car. The temperature outside your car is 30 degrees  below freezing. 2. When you put your cell phone (-20 degrees Celsius) (A) on the car seat (B) in such a way that  the sun cannot reach it, the cell phone becomes warm. 3. Water (A) in a cup sitting in a microwave oven (B) gets warm. 4. Water (A) in a pan sitting on an electric stove which is connected to an (electrical outlet = B)  becomes warm. 5. Water (A) in a pan sitting on an electric (stove = B) becomes warm. 6. You (A) inflate the tire of your bike and the air (B) in the pump becomes warm.
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Unformatted text preview: 7. Your hands (A) get warm facing a fire (B). 8. Your hands (A) get warm not by facing a fire but by you being in a warm room (B) in which there is a fire place. 9. Your hands (A) get warm by you (B) by rubbing them against each other. 10. Your hands (A) get warm by holding a hot cup (B) of tea. 11. The tires (A) of your car become warm after a long trip on a very cold road (B). 12. A hot tea (A) becomes cold in a cup (B). 13. A hummer’s head (A) becomes warm after being used to hit nails for a long time by you (B). 14. A hummer’s metal (A) head becomes warm while being held by you (B). Answer: 8w and 6q TOUPADAKIS © AT WINTER2009...
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