System of Particles and Rotational Motion

Rotational equivalent of force

Torque is the rotational analog of force, causing angular acceleration and representing the effectiveness of a force in producing rotation.

All particles have the same velocity

In pure translation, every particle of the body moves with the same velocity at any instant of time.

v = ωr

Linear velocity is the product of angular velocity and the radius of rotation, where r is the perpendicular distance from the axis.

Total external torque is zero

When total external torque is zero, angular momentum remains constant in a system.