Linear Motion

If a moving body changes its position with time along a straight line, then it is said that the body is in linear motion. You can easily understand the linear motion of objects by considering the following examples.

• Motion of an ant along the edges of a rectangular table

• Motion of a car along a straight road

• Motion of a rolling ball over an inclined plane

Distance and displacement

Distance is defined as the ground covered by a moving object during its motion. Its SI unit is metre (m). It has only magnitude but no direction. Distance can never be negative. The minimum value of distance is zero.

Displacement is defined as how far an object has moved relative to the starting point. Its SI unit is metre (m). It has both magnitude and direction. Displacement can be positive, negative, or zero.

The distinction between these two quantities becomes evident by considering the following situation.