A small ball is projected at an angle `alpha` between two vertical walls such that in the absence of the wall its range would have been `5d`. Given that all the collisions are perfectly elastic, find.
(a) maximum height atained by the ball.
(b) total number of collisions with the walls before the ball comes back to the ground, and
(c) point at which the ball finally falls. The walls are supposed to be very tall.

Options

A. `5`
B. `7`
C. `9`
D. `11`

Answer

C

Explanation

Vertical component of velocity of the ball do not change after collision.