Stopping Distance

This lesson covers stopping distance, thinking distance, braking distance, and the factors that affect each — as required by the Edexcel GCSE Physics specification (1PH0), Topic 1: Key Concepts of Physics. You need to understand the equation linking these distances, know the factors that affect each, and understand the dangers of large decelerations.

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What Is Stopping Distance?

When a driver sees a hazard and applies the brakes, the car does not stop instantly. The total distance it takes to stop is called the stopping distance.

stopping distance = thinking distance + braking distance

Thinking Distance

Thinking distance is the distance the vehicle travels during the driver's reaction time — the time between seeing the hazard and pressing the brake pedal.

During the thinking distance, the vehicle continues at the same speed because no braking force has yet been applied.

thinking distance = speed × reaction time

Braking Distance

Braking distance is the distance the vehicle travels after the brakes are applied until it comes to a complete stop.

During the braking distance, the braking force decelerates the vehicle.

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Reaction Time