Stopping Distances

• What is the definition of stopping distance for a car?

  The total distance travelled during the time it takes for a car to stop in response to an emergency
• How can stopping distance be expressed mathematically?

  Stopping distance = Thinking distance + Braking distance

  
• What is thinking distance?

  The distance travelled in the time it takes the driver to react

  
• What is braking distance?

  The distance travelled under the braking force
• How does speed affect stopping distance?

  The greater the speed of the vehicle, the greater the stopping distance
• If a vehicle is travelling at 20 m/s and has a stopping distance of 40 metres, what is the thinking distance if the braking distance is 26 metres?

  The thinking distance is 14 metres

  
• How do you calculate braking distance from stopping distance and thinking distance?

  Braking distance = Stopping distance - Thinking distance

  
• What is the braking distance if the stopping distance is 40 m and the thinking distance is 14 m?

  The braking distance is 26 m

  
• What is the relationship between vehicle speed and stopping distance according to the UK Highway Code?

  At 20 mph the stopping distance is 12 m, while at 60 mph it is 73 m

  
• What does the area under a velocity-time graph represent during an emergency stop?

  The area represents the distance travelled

  
• What happens to the vehicle's speed while the driver reacts?

  The vehicle continues moving at a constant velocity
• How is the braking distance calculated from a velocity-time graph?

  It is the area under the graph during the car's deceleration

  
• If a driver takes 1 second to react before applying the brakes, what is the driver's reaction time?

  The driver's reaction time is 1 second

  
• What is the typical range of human reaction time for an alert person?

  0.2 - 0.9 seconds
• How can human reaction time be measured using a ruler drop test?

  The distance the ruler falls indicates the reaction time

  
• What factors can increase thinking distance?

  Tiredness, distractions, and intoxication
• What is the relationship between thinking distance and speed according to the graph?

  The thinking distance is directly proportional to the speed of the car

  
• How does a tired driver's reaction time compare to an alert driver's reaction time?

  A tired driver's reaction time is greater

  
• What is the definition of braking distance?

  The distance travelled by a car under the braking force
• What are the main factors affecting braking distance?

  Speed, vehicle condition, road condition, and vehicle mass
• What happens to the kinetic energy of a car when brakes are applied?

  The kinetic energy decreases and thermal energy of the brakes increases

  
• How does braking force relate to vehicle speed?

  The greater the speed, the greater the braking force required to stop the vehicle
• If a car has a total kinetic energy of 168,750 J and stops, how much work is done by the braking force?

  The work done is 168,750 J

  
• How do you calculate braking distance using work done and braking force?

  Distance = Work done ÷ Braking force

  
• What is the braking distance if the work done is 168,750 J and the braking force is 6000 N?

  The braking distance is 28.1 m
• Why does the temperature of the brakes increase when a vehicle stops?

  Work is done by the frictional force between the brakes and the wheel

  
• What is the relationship between braking distance and speed squared?

  The braking distance is proportional to the speed squared

  
• What happens to braking distance at very high speeds?

  The brakes get hot and become less effective, increasing braking distance