A stone tied to a rope is rotated in a vertical circle with a uniform speed. If the difference between the maximum and minimum tensions in the rope is 20 N, mass of the stone in kg is $( g = 10\: ms^{-2})$

Question

$\begin {array} {1 1} (1)\;0.75 & \quad (2)\;1.0 \\ (3)\;1.5 & \quad (4)\;0.5 \end {array}$