A horizontal cylinder is fixed, its inner surface is smooth and its radius is $R$. A small block is initially at the lowest point. The minimum velocity that should be given to the block at the lowest point, so that it can cross the point $P$ is $u$, then

When block projected anticlockwise $h = R + R \sin 30° = 3 R/2$

If $u$ is the velocity to reach the point $P$, then $u = \sqrt{2gh} = \sqrt{ 2g\times \frac{3R}{2}}=\sqrt{3gR}$

Therefore to cross point $P, u >\sqrt{3gR}$

If the block moves clockwise then it will complete a vertical revolution along the inner surface of the cylinder if u $>\sqrt{5gR}$