Question

Ethel is sitting on a park bench feeding the pigeons when a child's ball rolls toward her across the grass. Ethel returns the ball to the child by hitting it with her 2.0-kg pocketbook with a speed of 20 m/s. If the impact lasts for 0.4 s, with what force does Ethel hit the ball?

Answer 1

100N

Step-by-step explanation:

Given parameters:

Mass of pocketbook = 2kg

Velocity = 20m/s

time of impact = 0.4s

Unknown:

Force Ethel hits the ball = ?

Solution:

The impact can be best pictured as the impulse of the ball on the pocket book. Impulse is the time taken for a force to act.

Impulse = Force x time

Impulse is the same as momentum;

Momentum = mass x velocity

therefore equating impulse and momentum;

Force x time = mass x velocity

Force =
`(2 x 20)/(0.4)` = 100N