Braking

• The stopping distance of a vehicle is the sum of the thinking distance and the braking distance
• Thinking distance is the distance the vehicle travels during the driver’s reaction time
• Braking distance is the distance the vehicle travels under the braking force
• For a given braking force the greater the speed of the vehicle, the greater the stopping distance
• Reaction times vary from person to person and typical values range from 0.2 s to 0.9 s
• A driver’s reaction time can be affected by

  • Tiredness
  • Drugs
  • Alcohol
  • Distractions
• The braking distance of a vehicle can be affected by adverse road and weather conditions ( wet and icy ) and poor condition of the vehicle (brakes and tyres).
• When a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases
• The greater the speed of a vehicle the greater the braking force needed to stop the vehicle in a certain distance
• The greater the braking force the greater the deceleration of the vehicle
• Large decelerations may lead to brakes overheating and/or loss of control