Stopping distance

• Reaction distance


  Distance traveled by vehicle during reaction time
• Reaction distance is affected by reaction time, vehicle speed, road surface, gradient, vehicle weight, and brake condition
• Stopping distance


  Sum of reaction distance and braking distance
• Stopping distance formula: d = 5Vt/18+ v^2/170
• Stopping distance calculation


  • Trevor driving at 45 km/h with 0.75 s reaction time
  • calculate the stopping distance using the formula
  • d= 5Vt/18+v^2/170.
  • stopping distance is 21m
• Solving stopping distance


  1. Write formula

  2. Substitute values

  3. Evaluate

  4. Express answer

  5. Write answer in words
• Reaction time averages 0.75 seconds for a fit and healthy driver