Question

how can you say that a body is in motion?is it a common factor

Answer 1

a body is siad to be in motion if it's position is continuously changing with respect to a frame of reference. when a body is in motion it possesses kinetic energy.
hope it answers your query.

Answer 2

here is the answer to your question:-

We can say that the body is in motion when it is changing is position with respect to time.

Also, if an object moves with respect to surroundings then also it is in motion.

Hence, we can say that a body is in motion it changes its state of action or movement.

Remember one more thing
that motion is described in terms of displacement, distance, velocity, acceleration, time and speed.

hope this will help.