Question

Can a motion that is periodic relative to one observer be non-periodic relative to another?

• A. True
• B. False

Answer 1

The correct option is A

True

A body executes periodic motion about another body.

Particle A is going in a circle with fixed speed in the x-y plane. Can you think of a frame from where if looked the motion of A isn't periodic?

Let's assume I am also going in a circle of the same radius as A with the same speed, so I am always hovering over A.

To me A will look like as if it is at rest, and not doing a periodic motion.

So yes periodic motion is a relative term as is motion.