Two point masses `m` are connected the light rod of length `l` and it is free to rotate in vertical plane as shown in figure. Calculate the minimum horizontal velocity is given to mass so that it completes the circular motion in vertical lane.

Explanation

Here tenstion in the rod at the top most point of circle can be zero or negative for completing the loop. So velocity at the top most point is zero.
From energy conservation,
`1/2mv^2+1/2mv^2/4=mg(2l)+mg(4l)+0`
`v=sqrt((48gl)/(5))`