Question

Two equal and opposite forces are applied tangentially to a uniform disc of mass $M$ and radius $R$ as shown in the figure. If the disc is pivoted at its centre and free to rotate in its plane, the angular acceleration of the disc is

Answer 1

Net torque on the disc is $2FR+2FR=4FR$ we added the torques because both have tendency to rotate the disc in $same$ $sense$

we have following formula for angular acceleration as $\alpha =\frac{torque}{\text{moment of inertia}}$ =$\frac{4FR}{\frac{M{R}^2}{2}}$ = $\frac{8F}{MR}$ it is the required answer.