Q 1 :    

A rigid ball of mass m strikes a rigid wall at 60° and gets reflected without loss of speed as shown in the figure. The value of impulse imparted by the wall on the ball will be  [2016]

[IMAGE 19]
 

  • mV

     

  • 2mV

     

  • mV2

     

  • mV3

     

(1)

[IMAGE 20]

Given, pi=pf=mV

Change in momentum of the ball = pf-pi

=-(pfxi^-pfyj^)-(pixi^-piyj^)

=-i^(pfx+pix)-j^(pfy-piy)

=-2pixi^-0j^=-mVi^

Here, pix=pfx=picos60°=mV2

   Impulse imparted by the wall = change in the momentum of the ball = mV