Question

A ball of mass $m$ moving with velocity $\vec{u}=u_x\hat{i}+u_y\hat{j}$ hits a vertical wall of infinite mass as shown in the figure. The ball slips up along the wall for the duration of collision and there is friction between the ball and the wall. Neglect the effect of gravity. Pick up the correct alternative.

• A. The wall provides the ball with net impulse along the negative x-axis for the duration of collision.
• B. The collision changes only the x-component of velocity of the ball
• C. The collision changes only the y-component of velocity of the ball
• D. The impulse provided by frictional force to the ball for the duration of collision cannot be neglected in comparison to impulse provided by normal reaction

Answer 1

Answer: (D)

The wall exerts an impulsive normal reaction N on the ball along negative x-direction. Hence wall also exerts a friction force $\mu N$ on the ball in negative $y$-direction. Hence both x and y components of velocities are changed. Hence d is only correct choice