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 2s. The ball is in constant with the inclined plane throughout the process. What is the inclination angle of the plane?

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^(@)`