## 7th edition 4A.3

$\Delta U=q+w$

Alyssa Bryan 3F
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am
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### 7th edition 4A.3

Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump if 3.0 cm and the pump is depressed 20. cm with a pressure of 2.00 atm. (a) how much work is done in the compression? (b) is the work positive or negative with respect to the air in the pump? (c) what is the change in internal energy of the system?
I was able to answer parts a and b of the question but seem to not be able to figure out part c. How do I go about solving part c?

Jane Burgan 1C
Posts: 73
Joined: Fri Sep 28, 2018 12:15 am

### Re: 7th edition 4A.3

The change in internal energy is equal to q + w. In this problem, q is 0 because there's no heat given off or absorbed as energy, so the change in internal energy is just equal to w. From parts a and b, you know the work value so the change in internal energy will be equal to the work value you solved!