A rigid ball of mass $M$ strikes a rigid wall at an angle of $30^{\circ}$ to the wall and gets refle

Question

A rigid ball of mass $M$ strikes a rigid wall at an angle of $30^{\circ}$ to the wall and gets reflected without loss of speed $V$. The value of impulse imparted by the wall on the ball will be

Professor PC Thomas Classes · Answer

The angle with the wall is $30^{\circ}$, so the angle with the normal is $60^{\circ}$. Let's use the angle with the wall $	heta = 30^{\circ}$. Component of velocity parallel to the wall remains unchanged. Component perpendicular to the wall changes from $V\sin(30^{\circ})$ to $-V\sin(30^{\circ})$. Change in momentum = $2MV\sin(30^{\circ})$. (Note: if angle is with normal, it would be $2MV\cos	heta$).