Rotational Motion and Equilibrium

Rotational Motion and Equilibrium

Radian:

A unit of rotational displacement; one revolution equals 2 ∏ radians.

Angular Velocity:

• Also called rotational speed, the number of rotations or revolutions per unit of time, often measured in rpm, revolutions per minute.

Table of rotational motion formulas, and the related linear motion formulas:

Linear motion formula	Rotational motion formula

Torque:

The rotational quantity that causes rotation; the product of force times lever arm.

Moment of inertia:

• Also called rotational inertia, The rotational equivalent of linear inertia; a measure of the ease of rotating some object.

Newton�s second law for rotational motion:

• Σ Ƭ=I α The sum of the torques is equal to the rotational inertia times the angular acceleration.

Rotational Equilibrium:

• The situation when the net torque on an object equals zero.

Angular momentum:

• The rotational equivalent of linear momentum that describes the tendency of an object to continue rotating.