Science Chapter 09: Motion and Time

The distance moved by an object in a unit time is called its speed. Speed of objects help us to decide which one is moving faster than the other. The speed of an object is the distance travelled divided by the time taken to cover that distance.

Its basic unit is metre per second (m/s).

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.