how is rest & motion related to each other?

Hi Ajl!

Motion is a change in position of an object with respect to time. For example, a car running on the road is said to be in motion.

If a body A is not moving with respect to another body B, we can say that the body A is at rest with respect to B.

Rest and motion are relative. For example, if we are riding a car, we are rest with respect to the car. But we are in motion with respect to the road.

Hope this is clear to you.