Warm-Up Exercise 8

Due 10:00 am, Mon, Jan. 23

Physics 123, Winter Semester, 2012

In your own words, and without referring to the text if possible, why are things like temperature, internal energy, volume, pressure "state variables"? (What is a state variable, anyway?)


Enter "-", "+", or "0" for the quantities Q, W, and ΔE_int (three entries on each line) for the following situations (this is Quick Quiz 20.3 in the Eigth edition of the text).
(A) Rapidly pumping up a bicycle tire (the system in question is the air in the pump)
(B) Luke warm water in a pan on a hot stove (the system in question is the water in the pan)
(C) Air quickly leaking out of a balloon (the system in question is the air that was originally in the balloon)


In the P-V diagram above, characterize the paths isobaric, isovolumetric, isothermal, or adiabatic. Which processes do you think are more common in typical engineering situations (motors, heaters, calorimeters, refrigerators, leaf blowers, etc.)?