Oscillatory Motion
- Repeat itself regularly for example pendulum of a wall clock
- Display irregularity for example earthquake
Periodic Motion – This motion repeats at equal interval of time T.
Period of Oscillatory – The time taken for one repetition is called period.
Frequency - 
, It is defined reciprocal of time period.
The condition of the periodic motion is
(1.10)
where motion is designated by time function x(t) .