The equivalent of linear momentum in rotational motion is angular momentum. It is the property of a rotating body given by the product of a moment of inertia and the angular velocity of a rotating object.
- The Angular Momentum of a rotating body is proportional to its mass and to how rapidly it is turning.
- In addition, the angular momentum depends on how the mass is distributed relative to the axis of rotation: the further away the mass is located from the axis of rotation, the greater the angular momentum.
- A flat disk such as a record turntable has more angular momentum than a tall cylinder of the same mass and velocity of rotation.
- Like linear momentum, angular momentum is a vector quantity, and its conservation implies that the direction of the spin axis tends to remain unchanged.
- For this reason, the spinning top remains upright whereas a stationary one falls over immediately.