Speed and motion graphs

A motorised trolley on a level track. Its motor follows the plan part by part, and at the start of each part it changes its speed smoothly, by 0.5 m/s in each second, so the corners of the distance–time line are slightly rounded. There is no friction loss or wheel slip.

The motion sensor measures the distance from its face to the card on the back of the trolley, ten times a second, with no noise. The pulses on the screen are slowed down enormously: real ultrasound crosses 2 m in about 6 thousandths of a second.

The speed–time journeys are made of straight pieces, and the distance travelled is the area under them, worked out exactly. Real readings are taken in a lab; this is simulated apparatus.

With reduced motion each run is drawn complete at once, and the trolley moves straight to where it stops.