Question

how can you say that a body is in motion ? is it acommon property?

Answer 1

motion of a body depends upon reference frame. if according to a reference frame you change your position with respect to time then you are in motion but if I m moving with same speed as you are then according to my reference frame you are at rest because you are not changing your position with respect to time in my reference frame.

motion Is not a property. it is the effect of force

Answer 2

if a object is changing its position with respect to time and with respect to stationary object