Stopping distance = reaction distance + braking distance
Before your car comes to a stop, two distances add up: the reaction distance (you keep moving until your foot brakes) and the braking distance (the car slows down). With two simple rules of thumb (dry road, normal braking):
- Reaction distance = (speed ÷ 10) × 3
- Braking distance = (speed ÷ 10) × (speed ÷ 10)
At double the speed, braking distance doesn’t double – it quadruples.
Good to knowIn an emergency stop the braking distance is roughly halved. On a wet road it grows much longer – on ice, many times over.
Centrifugal force: what pushes you out of the bend
In a curve a force acts outwards – the centrifugal force. It also rises with the square of speed: double the speed means four times the force. Only your tyres’ grip can hold against it.
The faster and tighter the curve, the harder it pushes you outward.
Vehicle & assistants
- Roadworthiness: tyres (tread, pressure), brakes, lights, fluids – your responsibility. The tyres are the only link to the road, together about the size of four palms.
- Secure your load: loose objects become projectiles under braking.
- Assistance systems: ABS (wheels don’t lock, you stay steerable), ESP (anti-skid), lane-keeping and emergency-braking assistants help – but they don’t cancel physics.