Question 8.3 6th edition

[Samantha Man 1L]

"Air in a bicycle pump is compressed by pushing in the handle. If the inner diameter of the pump is 3.0 cm and the pump is depresses 20 cm with a pressure of 2.00 atm, how much work is done in the compression? I know I need to use w=-p(delta(v)) to find work, but I'm not sure how to find volume in this case.

[Janice Park 1E]

Hey! To answer your question:
A bicycle pump is like a cylinder, so to find volume, we'd want to use the volume equation for a cylinder, being pi * radius^2 * height (or in this case, distance depressed). Since radius is 1/2*diameter, the radius is 1.5cm. From this, you'll get pi*(1.5cm)^2*(20cm), or about 140 cm^3, which we can convert to liters, as 0.14 L. However, the change in volume is going to be negative, because the pump is being depressed, and is going from a larger volume to a smaller volume, so delta(V) will be -0.14L.

[deniise_garciia]

Thanks Janice!!
I was also wondering how to go about this problem, thank you for clarifying!