A second is the relations between force and momentum, . The rotational equivalent is that any change in a system's angular momentum is caused by a net torque acting on the system.

The third involves the angular analog of linear impulse . The rotational equivalent is the angular impulse . Any time you give an object a spin, you are imparting an angular impulse to the object through the torque you apply. This in turn causes the system's angular moment to change. Equivalent to is

• The first relationship is not always true if the system is not a rigid body. Even for rigid bodies it may not be true if they are not rotating about a fixed axis. However, the second and third forms are always true even for a system of independent particles.