Textbook HW 4A.3

[AndresElizarraras 2A]

Textbook problem 4A.3 asks us to solve work of air compressed in a cycle pump using the equation W = -pdV

Pressure (P) is given to us as 2.00 ATM where the change in volume (dV) must be solved for in order to obtain work.

Solving for dV, we use the area of a circle * the diameter to obtain the volume.

But why use a circle as our point of reference for solving volume? What implies we must use a circle? Are bicycle pumps not rectangular?

[Jackson Crist 1G]

I just assumed it was one of those hand pumps that are used for like basketballs and footballs. Those are basically always circular (cylindrical shape), so that's why [I think]. Feel free to correct me if I'm wrong, anyone.