Question

Why it is said that motion is a relative term

Answer 1

1. Yes, motion is a relative term.
2. Imagine you are in a spaceship in space. You look outside and it's completely dark. There is nothing else than dark space. Now even though the spaceship is moving in any direction with any speed, you feel you are at rest because there is nothing you see relative to which you are moving. So you need relative objects to see motion.
3. Now if you are moving in some direction and you cross another spaceship, you feel that it was coming in the reverse direction and crossed you while you were at rest.
4. Similarly, if you are sitting in a car moving on a road, a person standing on the road would feel that the car and all the people in it are moving forward.
5. You will feel the man is moving backward and the people with you are at rest.
6. So it only depends on the objects relative to which you see motion. If you change it, motion changes.