Motion

A delivery van leaves a depot at half past seven and returns four hours later. Nobody followed it. Nobody watched it park, pull away, sit in traffic or take the long way round the ring road. Yet the tracker in the cab hands the depot manager a single line on a chart, and from that line alone she can say when the van was moving, when it stopped, which leg of the journey was the fastest and how far it went in total. The line is a distance-time graph, and reading one is a skill you can learn in an afternoon and use for the rest of your life.

This lesson teaches you to read that line and to do arithmetic with it. You will meet the one equation the Physics Equation sheet prints for this topic, learn why physicists insist on two words for going fast rather than one, and find out how a slope on a piece of graph paper turns into a number in metres per second. By the end you will be able to look at a set of coordinates you have never seen before and describe the journey they record, which is exactly what the physics paper will ask you to do, on both tiers.