Question 4

Figure to be added

A winding, curved path running from point A to point B. The path is labelled 400 m, and the straight line from A to B is marked with a dashed arrow labelled 120 m.

A child starts at A, walks 400 m along the winding path shown above, and arrives at B. What is the magnitude of their displacement?

The right answer is the one marked above.

120 m. The magnitude of the displacement is the straight-line distance between the starting point and the finishing point — here AB = 120 m. Its direction is from A towards B.

400 m is the distance travelled, not the displacement. The more the path winds, the further apart distance and displacement become; only when the path is perfectly straight are the two equal.