Relative Motion

Key Stage 3

Meaning

Relative motion is how fast an object appears to be moving when the observer is also moving.

About Relative Motion

Objects can appear to be moving faster or slower if the observer is moving as well.

Examples

If a van is travelling at 30m/s and a car overtakes the van at 35m/s, it appears to the van like the car was only travelling at 5m/s.

If a truck is travelling at 20m/s towards a car which is travelling at 30m/s. It appears to the truck as if the car is travelling and 50m/s.