A football player kicks a 0.41-kg football initially at rest; and the ball flies through the air. If the kicker's foot was in contact with the ball for 0.051 s and the ball's initial speed after the collision is 21 m/s, what was the magnitude of the average force on the football?
A)9.7 N
B)46 N
C)81 N
D)170 N
E)210 N

Question

Quizplus · Accepted Answer

We can use the impulse-momentum theorem to solve this problem. The impulse acting on the ball is equal to the change in momentum of the ball:

Impulse = Δp = mΔv

where m is the mass of the ball and Δv is the change in velocity of the ball.

Δv = 21 m/s (since the ball's initial velocity was 0)

The time of contact between the foot and the ball is 0.051 s, so the average force F can be calculated as:

F = Impulse / time = Δp / time = mΔv / time

F = (0.41 kg)(21 m/s) / 0.051 s = 170 N

Therefore, the answer is D) 170 N.

A Football Player Kicks a 0