Distance and displacement

From distance to displacement — how they differ

Follow one object moving through space and watch how the two quantities behave differently at each stage.

1. 1The object starts movingAt the moment the object leaves its starting point, both distance and displacement are zero. They are about to diverge — distance will track every metre of path, displacement will track only the straight-line gap.+
2. 2Object travels along a curved or winding pathDistance increases with every metre of path travelled, regardless of direction. Displacement, however, is only the straight-line distance from the start to the current position — it can be much smaller than distance if the path has turned.+
3. 3Object changes directionWhen the object turns back towards its start, distance keeps growing (it never decreases). But the straight-line gap between start and current position — the displacement magnitude — shrinks. Direction of displacement also changes as the object turns.+
4. 4Object returns to the starting pointWhen the object arrives back at its start, displacement = 0 m because the straight-line distance from start to finish is zero. Distance = the full length of the path taken. This one scenario proves that distance and displacement are fundamentally different quantities.+
5. 5Recording the answer correctlyDistance is recorded as a magnitude only (e.g. 400 m) — no direction needed, because it is a scalar. Displacement must always be recorded as a magnitude AND a direction (e.g. 250 m north-east) — because it is a vector. Missing the direction loses marks.+

Stop and predict

Commit to an answer before you reveal — this is how the concept sticks.

A student walks 300 m from home to a shop, then walks 300 m back home. Which row correctly gives their distance and displacement for the whole journey?

Tap any cell to reveal it. Tap a column header to read one property down every item.