Question

A 0.060 kg ball hits the ground with a speed of –32 m/s. The ball is in contact with the ground for 45 milliseconds and the ground exerts a +55 N force on the ball.

What is the magnitude of the velocity after it hits the ground?

9.3 m/s
12 m/s
41 m/s
73 m/s

Answer 1

Impulse = FΔt = 55 N × 0.045 s = 2.475 N·s.
Δv = impulse / m = 2.475 / 0.060 = 41.25 m/s.
v_final = v_initial + Δv = −32 + 41.25 = +9.25 m/s.

Magnitude ≈ 9.3 m/s.