Relative Motion:

Up to this time, we have learned the motion of particles and rigid bodies w.r.t. a fixed set of reference axes. Sometimes this is essential to study the motions along with moving frame of reference. Let us assume a person moving on the deck of a boat which itself is sailing. If the observer is standing on the shore (supposed to be fixed) and is observing the motion of the moving person on the deck his observation shall be different than the motion observed through the observer which is it on the boat.

The motion of a particle or a rigid body along reference to fixed axes is termed as absolute motion. The motion of a particle or a rigid body with respect to a moving set of reference axes is called as relative motion.