A ball is thrown horizontally from a height of 20m. What is the time it takes to hit the ground?

To determine the time taken by the ball to strike the surface of piston A, we only need to consider the vertical motion of the ball.

Given:
Initial vertical velocity, $u_y = 0 \text{ m/s}$ (since the ball is thrown horizontally).
Vertical distance (height), $h = 20 \text{ m}$.
Acceleration due to gravity, $g = 10 \text{ m/s}^2$ (standard approximation).

We use the kinematic equation for vertical displacement:

$$s_y = u_y t + \frac{1}{2} g t^2$$