Factors Affecting Braking Distance
- The braking distance is defined as:
The distance travelled by a car under the braking force - i.e. whilst it is slowing down
- The main factor affecting the braking distance of a car is its speed
- The greater the speed, the greater the braking distance will be
- There are additional factors which affect the braking distance, such as:
- Vehicle condition - e.g. worn tyres or poor brakes
- Road condition - wet or icy roads make it harder to decelerate
- Vehicle mass - a heavy vehicle, such as a lorry, takes longer to stop
- The smoother the road conditions, for example when they are wet and icy, the less friction there is between the tyres and the road surface so there would be a greater braking distance
- The braking distance is the ratio of the kinetic energy of the car and the braking force
- This is because the work done in bringing a car to rest is the transfer of all its kinetic energy into other forms (thermal, sound)
- The kinetic energy is equal to
KE = ½mv2
- This means the braking distance is proportional to the velocity squared
- If the velocity doubles, the braking distance increases by (2)2 , 4 times!