A 120-g ball thrown at 25 m/s is struck by a bat which gives it a velocity of 30 m/s in the opposite direction.If the time of contact is 0.01 s,the magnitude of the average force experienced by the ball is
A)3000 N.
B)1000 N.
C)660 N.
D)60 N.

Question

Quizplus · Accepted Answer

The change in momentum of the ball is given by:
Δp = mvf - mvo
where m is the mass of the ball, vo is the initial velocity, and vf is the final velocity.
Δp = (0.12 kg)(-30 m/s) - (0.12 kg)(25 m/s) = -6 Ns
Since the time of contact is 0.01 s, the average force experienced by the ball is:
F = Δp / Δt = -6 Ns / 0.01 s = -600 N
The negative sign indicates that the force is in the opposite direction of the motion of the ball.
Taking the magnitude, we get:
|F| = 600 N ≈ 660 N (to two significant figures)

A 120-G Ball Thrown at 25 M/s Is Struck by a Bat