Approximate distance travelled in one second at common speeds

The official theory questions use these approximate values as minimum-distance references: about 9 metres at 30 km/h, 14 metres at 50 km/h, 28 metres at 100 km/h, 36 metres at 130 km/h and 42 metres at 150 km/h. They correspond roughly to the distance travelled in one second. They help estimate reaction distance and a minimum following interval, but are not a universally safe stopping distance. Avoiding a rear-end collision also requires allowance for braking distance and the driver, vehicle, road and traffic conditions.