Key Points - Motion and Time

-  Motion: The action or process of moving or being moved.
-  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.

Types of Motion:
(i) Uniform motion: An object moving along a straight line with a constant speed is said to be in uniform motion. The average speed is the same as the actual speed.
(ii) Non-Uniform motion: If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.

Speed: It is the distance covered by an object in a unit time. Basic unit of speed is m/s.
Speed= Total distance covered / Total time taken
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.