A 0.4 kg ball moving with a speed of $15 \mathrm{~m} / \mathrm{s}$ strikes a hard wall at an angle o

Question

A 0.4 kg ball moving with a speed of $15 \mathrm{~m} / \mathrm{s}$ strikes a hard wall at an angle of $60^{\circ}$ with the wall. It is reflected with the same speed at the same angle. If the ball is in contact with the wall for 0.1 seconds, the average force acting on the wall is

Professor PC Thomas Classes · Answer

Angle with wall $	heta = 60^{\circ}$. Change in momentum $\Delta p = 2mv \sin 	heta = 2(0.4)(15)\sin(60^{\circ}) = 12 	imes \frac{\sqrt{3}}{2} = 6\sqrt{3}$. Average force $F = \frac{\Delta p}{t} = \frac{6\sqrt{3}}{0.1} = 60\sqrt{3} \mathrm{~N}$.