Answer to Question #122870 in Physics for Bob Bell

Question

Two pistons are both in contact with a reservoir of fluid. Piston 1 has a cross-sectional area A1 = 0.0610 m2, and Piston 2 has a cross-sectional area A2 = 0.915 m2. The bottoms of the pistons are at the same level, and the pistons are in equilibrium.

Suppose a force, F1 = 22.0 N is exerted on Piston 1.
What is the pressure in the fluid just below Piston 1?

What is the pressure in the fluid just below Piston 2?

What is the force being exerted on Piston 2 to keep the two pistons in equilibrium?

Answer 1

The pressure in the fluid just below Piston 1 is

$$p_1=F_1/A_1=361\text{ Pa}.$$

The pressure in the fluid just below Piston 2 is the same according to Pascal's law:

$$p_2=p_1=361\text{ Pa}.$$

The force being exerted on Piston 2 to keep the two pistons in equilibrium is

$$F_2=p_2A_2=330\text{ N}.$$