A small block of mass of 0.1 kg lies on a fixed inclined plane PQ which makes an angle `theta` with the horizontal. A horizontal force of 1 N acts on the block through its center of mass as shown in the figure. The block remains stationary if (take g = `10` m/`s^(2)`)

Options

A. `theta=45^(@)`
B. `thetagt45^(@)` and a frictional force acts on the block towardsP.
C. `theta gt 45°` and a frictional force acts on the block P towards Q.
D. `theta lt 45°` and a frictional force acts on the block towards Q.

Answer

A, C

Explanation

Here, `m = 0.1 kg, g= 10 m s^(-2)`
`therforemg=0.1 xx 10= 1 N`
The various forces acting on the block are as shown in the figure

If `theta` = 45°, then `costheta = sintheta` 45°`, then `sintheta > costheta`
So frictional force acts on the block towards Q.
If plane is rough and `theta < 45°`, then `costheta > sintheta`
So frictional force acts on the block towards P.