Braking Forces & Road Conditions

What factors affect braking distance?

Vehicle speed, road conditions, tyre condition and brake condition.

Why do wet or icy roads increase braking distance?

They reduce friction between tyres and the road, reducing available braking force.

Why do worn tyres increase braking distance?

They may provide less grip, particularly on wet roads.

Why can poorly maintained brakes increase braking distance?

They may produce a smaller braking force, reducing deceleration.

Why does greater speed increase braking distance?

The vehicle has more kinetic energy, so more work must be done to stop it.

How does braking transfer energy?

Work done by friction transfers energy from the vehicle's kinetic energy store to thermal energy stores.

Why can very large decelerations be dangerous?

They may cause loss of control, and intense braking can contribute to brake overheating.

How does braking force affect deceleration?

A greater braking force produces a greater magnitude of deceleration, provided mass remains constant.

Why doesn't doubling speed simply double braking distance under the same constant braking force?

Kinetic energy is proportional to speed squared, so doubling speed approximately quadruples braking distance.