# How is angular momentum conserved for rotating systems?

##### 1 Answer

Oct 21, 2015

when external torque acting on a body is zero

#### Explanation:

Angular momentum is defined as rate of change of torque

J=dT/dt ( T- torque ) ,

if external torque acting on a body is zero , then J=d0/dt

but differentiation of any quantity is zero is it is a constant , so angular momentum remains constant is ext. toruqe is zero