Ahand-driven tire pump has a piston with a 2.50-cm diameter and a maximum stroke of 30.0 cm. (a) how much work do you do in one stroke if the average pressure is 2.40 ×10^{5} 5 n/m^2 2 ? (b) what average force do you exert on the piston, neglecting friction and gravitational force?

(a) you do a work on the piston: 35.34 (Joules) and (b) Average Force that you exert on the piston is: 117.81 (N)

Explanation:

We need to know that the work do it for a piston or boundary work of closed system is: where W is the work, P is the pressure and delta_V is the change in the volume. Now we need to remember that the volume for a piston is the same as: where L is the maximum stroke or length, so the piston volume is: therefore, piston's work is:. Then we are going to calculate the average force so we need to know that where P is the pressure, F is the force and A the area in this case the piston´s area, so and replacing values we get:

there are no contact forces mentioned on the list of choices that you've provided.