A runner completes one full lap around a 400 meter track. What is their displacement?

Displacement is a vector quantity that refers to the change in position of an object. It is defined as the shortest straight-line distance from the initial position to the final position, along with the direction of that line. In the case of a runner completing one full lap around a 400 meter track, the runner starts and ends at the same point.

Since displacement considers only the initial and final positions and not the path taken, the displacement in this scenario is zero. The runner has returned to their starting point, meaning there is no net change in position, which results in a displacement of zero meters. This understanding of displacement distinguishes it from distance, which would account for the entire length of the track covered by the runner. Thus, the correct response reflects this principle of displacement in physics.