Question

A ball of `50 g` strikes a smooth wall with speed `20 m//s` as shown. If collision is elastic and contact period is as shown . If collision is elastic and contact period is `2 xx 10^(-3) s` , the force exerted by the wall on the ball is

A. `250 N` to right
B. `250 N` to left
C. `500 N` to right
D. `500 N` to left

Answer 1

Correct Answer - C
The velocity component along the wall remains same (due to no force along the wall and the velocity component perpendicular to the wall just reverses (due to normal force)
`Delta p_(y) = 0`
`Delta p_(x) = mv cos 60^(@) - (-mv cos 60^(@))`
`= 2mv cos 60^(@) = mv`
`F_(x) = (Delta p_(x))/(Delta t) = (mv)/(Delta t) = ( 5 xx 10^(-3) xx 20)/(2 xx 10^(-3)) = 500 N` , to the right