Question

Suppose the resulting torque on a body is (i) zero (ii) not zero. What is the effect of the acting torques on the body in the two cases?

Answer 1

We know, torque is rate of change of angular momentum.

$\therefore \overrightarrow{N}=\frac{d\overrightarrow{L}}{dt}$

Now, if torque is zero, then angular momentum is constant and the body will be in stable equilibrium.

And if resultant torque is not zero, then angular momentum will be varying with time. Body will be processed unstable equilibrium and it will have rotation.