The forces $F_1$ and $F_2$ in a brake band and the direction of rotation of the drum are as shown in the figure. The coefficient of friction is $0.25$. The angle of wrap is $3\pi /2$ radians. It is given that $R$ = $1$ $m$ and $F_2$ = $1$ $N$. The torque (in $N$-$m$) exerted on the drum is _________
