GCSE Physics

Braking Factors

Just like thinking, there are many factors that affect how effective your braking will be:

BrakesWorn brakes won't work as well, so you'll need to brake for longer. Modern brakes are also better than old ones - they can apply bigger forces without causing skidding.
TyresNot all tyres are the same! Some are designed to reduce fuel consumption by rolling more easily. This is at the expense of grip in the wet. Tread patterns are designed to push water out from between the tyre and road. Good tyres can reduce braking distance by many metres! Worn tyres (with little tread) will have good grip in the dry but in the wet will lead to much longer braking distances...
Road SurfaceDifferent types of surface provide different levels of grip, especially in the wet. If the road is wet, braking distance will always be longer. Oil spills on the road, gravel, etc. all reduce grip and increase braking distances.
MassThe larger the total mass of the vehicle, passengers and luggage, the more kinetic energy it will have at a given speed. This increases the braking distance as it is harder to slow down.
AerodynamicsRather oddly, the worse your car's aerodynamics, the better it will be at slowing down during braking! The reason is that the airflow at and around the car (drag or air resistance) is an additional force acting to slow you.

The Mercedes SLR is so aerodynamic it has a flap that pops up on the boot to increase drag when braking!

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