5.8 Stopping Distances

• What is the definition of stopping distance?

  Total distance travelled to stop a car
• How is stopping distance calculated?

  Stopping distance = Thinking distance + Braking distance

  
• What is thinking distance?

  Distance travelled during driver reaction time

  
• What is braking distance?

  Distance travelled under braking force

  
• How does speed affect stopping distance?

  Greater speed increases stopping distance
• If a vehicle travels at 20 m/s, what is its stopping distance if the thinking distance is 14 m?

  26 m
• What does the area under a velocity-time graph represent?

  Distance travelled by the vehicle
• What happens to the vehicle's speed during braking?

  The vehicle decelerates to a halt
• What is the typical human reaction time range?

  0.2 - 0.9 seconds
• How can human reaction time be measured?

  By dropping a ruler and catching it

  
• What factors can increase thinking distance?

  Tiredness, distractions, intoxication
• How does tiredness affect a driver's reaction time?

  It increases the reaction time
• What is the relationship between speed and braking distance?

  Braking distance increases with speed

  
• What are some factors affecting braking distance?

  Vehicle condition, road condition, vehicle mass

  
• What happens to kinetic energy when brakes are applied?

  Kinetic energy is converted to thermal energy
• If a car has a mass of 1500 kg and a kinetic energy of 168,750 J, what work is done by the brakes?


  168,750 J

  
• How is braking distance calculated using work done?

  Distance = Work done ÷ Force

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

  28.1 m

  
• What is the effect of high speeds on braking effectiveness?

  Brakes may overheat and lose effectiveness
• What is the process of estimating decelerating forces?

  • Work done by brakes = transfer of kinetic energy
  • Braking distance is proportional to speed squared
  • Higher speeds increase braking distance significantly

  
• What are the key factors affecting stopping distance?

  • Thinking distance: affected by speed, tiredness, distractions, intoxication
  • Braking distance: affected by speed, vehicle condition, road condition, vehicle mass

  
• What happens to the temperature of brakes when a vehicle stops?

  • Work done by friction heats the brakes
  • Kinetic energy is converted to thermal energy
  • Increased brake temperature can lead to overheating

  
• How does the velocity-time graph illustrate stopping distance?

  • Area under the graph represents distance
  • Constant velocity during reaction time
  • Deceleration area represents braking distance

  
• What is the significance of reaction time in stopping distance?

  • Reaction time contributes to thinking distance
  • Delays in reaction increase overall stopping distance
  • Important for safe driving practices