Velocity is the rate of change of the position of an object. It is equivalent to the speed and direct of motion. Speed is a scalar quantity whereas velocity is a vector quantity. Velocity gives the magnitude and direction of motion. For example, if a car is moving at 100 km/h to the west, the velocity has been specified. If the velocity is constant, the object has a constant speed in a constant direction.

There are many equations of motion to calculate velocity.

v= Δx/Δt (1)

v=u+aΔt (2)

v^2= u^2+2aΔx (3)

Velocity can also be two-dimensional and expressed in polar coordinates. With polar coordinates, there are two types of velocity, radial and angular velocity. Radial velocity is the component of velocity away from or towards the origin. The angular velocity is the rate of rotation about the origin. The transverse velocity is the component of velocity along ta circle centered at the origin. The equation of velocity in a polar coordinate system is:

v=v_T+ v_R (4)

The magnitude of the radial velocity is a dot product. The equation is as followed:

v_R= (v*r )/(|r|) (5)

Where r is the displacement.