8.1 - Stopping Distances

• What is stopping distance?

  Minimum distance to stop a vehicle
• What is the formula for total stopping distance?

  Total stopping distance = thinking distance + braking distance
• What does thinking distance represent?

  Distance traveled during driver's reaction time
• What affects thinking distance?

  Speed of the vehicle and reaction time
• How does speed affect thinking distance?

  Higher speed increases thinking distance
• What factors can increase reaction time?

  Tiredness, drugs, distractions
• What is braking distance?

  Distance taken to stop after brakes applied
• What factors affect braking distance?

  Speed, mass, brake condition, traction
• How does speed affect braking distance?

  Higher speed increases braking distance
• What happens to kinetic energy as speed increases?

  Kinetic energy increases with speed
• How do worn brakes affect stopping distance?

  Worn brakes reduce stopping power
• What is the impact of wet or icy roads on stopping distance?

  Reduces friction, increases stopping distance
• What happens if tires are bald?

  Reduced grip on the road
• What is the relationship between speed and stopping distance?

  • Thinking distance increases proportionally with speed
  • Braking distance increases more quickly than expected
  • Doubling speed increases braking distance four-fold
  • Tripling speed increases braking distance nine-fold
• How does the graph of total stopping distance against speed appear?

  It gets steeper as speed increases
• What is the take-home message regarding speed and stopping distance?

  Higher speed leads to longer stopping distances
• 'Stopping distance' is the total distance a car travels from the moment when the driver first notices an obstruction, to when the car stops.
• Stopping distance equals:

  Thinking distance + braking distance
• Which of the following will slow a person's reaction time?

  Consuming alcohol

  Being distracted

  Tiredness

  Icy road surface

  • Consuming alcohol
  • Being distracted
  • Tiredness
• Which of the following will increase the braking distance?

  Being drunk

  Ice on the road

  Worn tyre tread

  Worn brakes

  • Worn tyre tread
  • Ice on the road
  • Worn brakes
• A vehicle drives twice as fast.

  What happens to the breaking distance?

  • The breaking distance increases by four times
  • If the vehicle speed increases by a factor of 2, then the breaking distance will increase by a factor 2 squared (22), so 4 fold. 
• Which factor affects both the thinking distance and the braking distance?

  Speed of the vehicle