Question 2
Three different routes join A to B — 320 m, 200 m and 240 m long. Which quantity has the same value no matter which of the three the child takes?
The right answer is the one marked above.
The displacement. Displacement depends only on the starting point and the finishing point — it is the straight-line distance between them, together with a direction. As long as the journey begins at A and ends at B, the route makes no difference.
The distance travelled is 320 m, 200 m or 240 m depending on the route, so it is not the same for all three. Distance is measured along the path actually taken; displacement is measured straight across.