A small block of mass m, can move without friction on the outside of a fixed vertical circular track of radiusR. The block is attached to a spring of natural length `R//2` and spring constant K. The other end of spring is connected to a point at height `R//2` directly above the centre of track.

If the complete stup is in a gravity free space, then the minimum speed (v_(0)) required at the highest point A to just reach the lowest point is

Options

A. `2R sqrt(k/m)`
B. `(3R)/2 sqrt(k/m)`
C. `R sqrt(k/m)`
D. Motion not possible in gravity free space.

Answer

C

Explanation

`1/2 m u ^(2)=1/2k(R)^(2)`
`u=Rsqrt(k/m)`