Q.What is meant by periodic and non-periodic motion ? Give any two examples, for each motion.

The distinguishing feature is regularity in time: periodic motion returns to the same state after a fixed, repeating time interval (the period), while non-periodic motion has no such fixed repeating interval.

Periodic motion: A motion that repeats itself, identically, after equal intervals of time is called periodic motion. The fixed time interval after which the motion repeats is called its time period.

Examples:

1. The revolution of the Earth around the Sun — repeats identically every 1 year.
2. The oscillation of a simple pendulum (small amplitude) — repeats identically every time period T = 2π√(L/g).

Non-periodic motion: A motion that does NOT repeat itself after equal (fixed) intervals of time is called non-periodic (or aperiodic) motion — there is no fixed period governing when the same state recurs.

Examples:

1. A leaf falling from a tree, drifting irregularly in the wind — its motion does not repeat in any fixed time pattern. …