Answer:
One has to understand the difference between distance and displacement.
Distance is a scalar. It tells us what is the total length of the curve (or line) representing the motion of the body from the initial position to the final position.
Displacement is a vector. It tells us what is the length along a straight line between the initial position and final position of the body.
So, a body may start at a particular point in space and travel for 10 seconds in such a way that at the end of 10 seconds its final position is exactly the same as the initial position.
In such a situation, even though the distance covered by the body during its movement for 10 seconds is a positive number, the displacement is zero because the distance between the initial position and final position is the same.
Explanation:
