## Angular Velocity:

It may be defined as the rate of change of angular displacement with the respect to time. It is usually expressed by the Greek letter ω (omega). Mathematically, angular velocity,

ω = dθ /dt

Since it has magnitude and direction, therefore, it is a vector quantity. It may be represented by a vector.

**Note:** If the direction of the angular displacement is constant, then the rate of change of magnitude of the angular displacement with respect to time is termed angular speed.

## Angular Acceleration:

It may be defined as the rate of change of angular velocity with respect to time. It is usually expressed by the Greek letter α (alpha). Mathematically, angular acceleration,

α = dω /dt =(d/dt)x(dθ/dt)=d

^{2}θ/dt^{2}

It is also a vector quantity, but its direction may not be sure as that of angular displacement and angular velocity.