A stone is projected from a horizontal plane. It attains maximum height `H` & strikes a stationary smooth wall & falls on the ground vertically below the maximum height. Assuming the collision to be elastic the height of the point on the wall where ball will strike is

Options

A. `(3H)/8`
B. `(3H)/4`
C. `H/2`
D. `H/4`

Answer

B

Explanation

`2x=R/2`
`x=R/4`
`y=x tan theta-1/2 (gx^(2))/(u^(2) cos^(2) theta)`
`=(2u^(2) sin theta cos theta)/(4g)xx tan theta-1/2 g xx(4u sin^(2) theta cos^(2) theta)/(u^(2) cos^(2) theta16g)`
`=(u^(2) sin^(2) theta)/(2g)-(u^(2)sin^(2) theta)/(8g)=(3u^(2) sin^(2) theta)/(8g)`
`=(3H)/4`