Question

A 0.5 kg ball moving with a speed of $12\text{m/s}$ strikes a rigid wall at an angle of ${30}^{\circ }$ with the wall. It is reflected with the same speed at the same angle. If the ball is in contact with the wall for 0.25 second, the average force acting on the wall is

• A. 96 N
• B. 48 N
• C. 24 N
• D. 12 N

Answer 1

The correct option is C 24 N

Component of momentum parallel to the wall add each other and component of momentum in the perpendicular to the wall are opposite to each other. Therefore change of momentum is:

final momentum - initial momentum
i.e., $mv\sin \theta \text{after collision}-(-mv\sin \theta \text{before collision})$
$\therefore F=\frac{2mv\sin \theta }{t}=\frac{2\times 0.5\times 12\times \sin {30}^{\circ }}{0.25}=24\text{N}$
Hence, the correct option is C.