Question

A ball after freely falling from a height of `4.9m` strikes a horizontal plane. If the coefficient of restitution is `3/4`, the ball will strike second time with the plane after
A. 1s
B. 1.5 s
C. 2 s
D. 3 s

Answer 1

Correct Answer - B
Velocity on hitting the surface = `sqrt(2 xx 9.8xx 4.9)`
`9.8 ms^(-1)`
Velocity after first bounce, `v=(3/4)xx9.8`
Time taken from first bounce to the second bounce = `(2v)/(g)`
`2 xx3/4 xxx 9.8 xx (1/9.8) = 1.5s`