Question

A constant torque acting on a uniform circular wheel changes its angular momentum from $A_0$ to $4A_0$ in $4\text{s}$. The magnitude of this torque is

• A. $\frac{3A_0}{4}$
• B. $4A_0$
• C. $A_0$
• D. $12A_0$

Answer 1

The correct option is A $\frac{3A_0}{4}$

Angular impulse = Change in angular momentum
$\therefore \tau \times t=L_f-L_i$
or $4\tau =4A_0-A_0$
$\therefore \tau =\frac{3A_0}{4}$.