Question

An athlete runs four laps of a $400\,m$ track. What is the athletes total displacement?
(A) $1600\,m$
(B) $- 400\,m$
(C) $0\,m$
(D) $400\,m$
(E) $1800\,m$

Answer 1

Displacement of a body is a vector quantity. The meaning of vector quantity means that it has a magnitude as well as a specific direction. It depends only on the body's initial position and final position and not the path taken by it.

Complete step by step answer:
Displacement is the change in position of a body in space. If a body moves from point $A$ to point $B$ then the displacement is the measurement that tells us by how much amount its position has changed. Simply to say, it is the segment joining the initial position and the final position of a body. Here, the displacement will be the line segment drawn by joining the point $A$ and $B$.
From the above statement, we can understand that displacement that displacement of a body depends on where it was initially and where it is now finally. It does not depend on the route that it takes. When the three bodies move from the same starting point and the end point is the same and the three bodies follow different routes, the displacement of the three bodies is the same. Then, the displacement of the circular area is zero, because the starting and the ending point is the same.

Hence, the option (C) is the correct answer.

Note: There may be confusion between the distance and displacement among the students. Displacement is a vector quantity and depends only on the initial and final position. Distance covered by a body is the total length travelled by the body along the path that it takes.