# A fly -wheel of mass 25 kg has a radius of $0.2\;m$. It is making 240 rpm. What is the torque necessary to bring to rest in 20 sec?

$\begin {array} {1 1} (1)\;2 \pi\; Nm & \quad (2)\;0.2\; \pi Nm \\ (3)\;\frac{2}{\pi}\;Nm & \quad (4)\;4 \pi\; Nm \end {array}$

(2) $0.2 \pi Nm$