Question

When is an object considered to be in motion

Answer 1

Motion can be defined as something that changes position over a period of time.

We can say that the object is in motion, when it changes its position after some time.

 A body in motion can be observed after attaching it with a frame of reference.

So if a body is changing position in the frame of reference it can be said to be in motion and if not then it is in rest.