Periodic events are used for the measurement of time.

Periodic motion of a pendulum has been used to make clocks and watches.

Motion of objects can be presented in pictorial form by their distance-time graphs.

The distance-time graph for the motion of an object moving with a constant speed is a straight line.

Uniform Motion ANd Non – Uniform Motion:

1. Uniform motion: An object moving with a constant speed is said to be in uniform motion. The average speed is the same as the actual speed.
2. Non-Uniform motion: If the speed of a moving object keeps changing, the object is said to be in non-uniform motion.

Speed: It is the distance covered by an object in a unit time.

Speed = Total distance/ Total Time

Basic unit of speed is m/s.

Distance-Time Graph: Motion of objects can be presented in pictorial form by their distance-time graphs.

The distance-time graph for the motion of an object moving with a constant speed is a straight line.