An inclined plane makes an angle `30^(@)` with the horizontal. A groove (OA) of length 5m cut in the plane makes an angle `30^(@)` with OX. A short smooth cylinder is free to slide down under the influence of gravity. The time taken by the cylinder to reach from A to O is `(g=10ms^(-2))`.

Options

A. `4s`
B. `2s`
C. `3s`
D. `1s`

Answer

B

Explanation

Acceleration of cylinder down the plane is
`a=(gsin30^(@))(sin30^(@))=10((1)/(2))((1)/(2))=2.5m//s^(2)`
time taken: `t=sqrt((2(s)/(a)))=sqrt((2xx5)/(2.5))=2s`