A body projected from the ground reaches a point 'X' in its path after 3 seconds and from there it reaches the ground after further 6 seconds. The vertical distance of the point 'X' from the ground is (acceleration due to gravity =`10ms^(-2)`)

Options

A. 30m
B. 60m
C. 80m
D. 90m

Answer

D

Explanation

Given `g=10ms^(-2)`.
Total flight time (t) `=(24)/(g)`.
`9 =(24)/(g)`.
`rArr u=(9g)/(2)`
`rArr u=(xx10)/(2)`.
`u=45`.
`h=ut -(1)/(2)gt^2`.
`=45 xx 3-(1)/(2) xx 10 xx(3)^2`.
`=135-45`.
`=90 m`.