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When you use a hand pump to inflate the tires of your
Chapter 19, Problem 14DQ(choose chapter or problem)
When you use a hand pump to inflate the tires of your bicycle, the pump gets warm after a while. Why? What happens to the temperature of the air in the pump as you compress it? Why does this happen? When you raise the pump handle to draw outside air into the pump, what happens to the temperature of the air taken in? Again, why does this happen?
Questions & Answers
QUESTION:
When you use a hand pump to inflate the tires of your bicycle, the pump gets warm after a while. Why? What happens to the temperature of the air in the pump as you compress it? Why does this happen? When you raise the pump handle to draw outside air into the pump, what happens to the temperature of the air taken in? Again, why does this happen?
ANSWER:Solution to 14DQ (a)Step 1 When we use a hand pump to inflate the tires, we would pull the piston to intake air and push the piston to push it through the tires. The hand pump works as a hand- held piston. We are providing external work to the system. Since the hand pump is not thermally insulated, the temperature which is increased by compressing the air would be delivered to surroundings to maintain thermal equilibrium. Thus, the hand pump gets hot when it is used for a while. (b)