A small ball is projected up a smooth inclined plane with an initial speed of `10 m//s` along the direction at `30^(@)`to the bottom edge of the slope .It returns to the edge after `2 s` . The ball is in contact with the inclied plane throughout the process. The angle of inclination `theta` is `:-`.

Options

A. `15^(@)`
B. `60^(@)`
C. `37^(@)`
D. `30^(@)`

Answer

D

Explanation

Along y-axis
`S_(y)=u_(y)t+1/2 a_(y)t^(2)`
here from O to P
`S_(y)=0, " "t=2` sec, `a=g sin theta`
`u_(y)=10 sin 30=5m//s`
`0=5xx2-1/2xx10sin thetaxx4`
`1=2 sin theta`
`sin theta=1/2`
`theta=30^(@)`