Differentiate between periodic and non-periodic motions by giving an example of each.

Periodic motion : A motion which gets repeated after regular intervals of time is called a periodic motion. 

Examples : The earth moving around the sun takes 365 days to complete one revolution and this motion gets repeated after every 365 days. 

Non-periodic motion : The motion which does not repeat itself after regular interval of time is called non-periodic motion. 

Examples : A footballer running on a field, application of brakes in a moving vehicle, a ball rolling down the ground gradually slows down and finally stops, motion of tides in the sea, etc