Question

A rigid ball of mass m strikes a rigid wall at ${60}^o$ and gets reflected without loss of speed as shown in the figure below. The value of impulse imparted by the wall on the ball will be :

• A. $2mV$
• B. $mV$
• C. $\frac{mV}{3}$
• D. $\frac{mV}{2}$

Answer 1

Answer: (B)

Initial momentum of the ball perpendicular to the wall

$P_i=m(-Vcos{60}^o)=\frac{-mV}{2}$

Final momentum of the ball perpendicular to the wall

$P_f=m\left(Vcos{60}^o\right)=\frac{mV}{2}$

Thus impulse imparted to the wall

$I=P_f-P_i=\frac{mV}{2}-\frac{-mV}{2}=mV$