Stopping Distance of a Vehicle

Key Objectives

• Understand what is meant by the stopping distance of a vehicle.
• Estimate how the stopping distance varies with speed.
• Describe factors affecting thinking distance and braking distance.

Stopping Distance Overview

• Stopping Distance: Total distance travelled from when a driver spots an obstruction to when the car stops.
• Composed of:
  • Thinking Distance: Distance travelled during the driver's reaction time.
  • Braking Distance: Distance travelled from when brakes are applied to when the car stops.

Factors Affecting Stopping Distance

• Speed: Greater speed increases stopping distance, assuming the same braking force is applied.
• Example: A car at 30 mph takes about 23 meters (approximately 6 car lengths) to stop.

Thinking Distance

• Depends on the driver’s reaction time, which varies from 0.2 to 0.9 seconds.
• Measuring Reaction Time:
  • Use a ruler drop test to measure how far a ruler falls before being caught.
• Factors Increasing Reaction Time:
  • Fatigue: Tired drivers react slower.
  • Alcohol and certain drugs: Prolong reaction time.
  • Distractions: E.g., mobile phones increase reaction time.
• Result: Increased reaction time increases thinking distance.

Braking Distance

• Affected by road and vehicle conditions:
  • Wet/Icy Conditions: Reduce friction, increasing braking distance.
  • Worn Tires: Reduce road friction, increasing braking distance.
  • Worn Brakes: Lead to longer braking distances.

Summary

• Both thinking and braking distances contribute to stopping distance.
• Various factors, including speed, driver condition, and vehicle condition, affect these distances.
• Important to maintain good vehicle condition and avoid distractions for minimal stopping distances.

Next Steps

• Further exploration on brakes in the next video.
• Questions on stopping distance available in the provided vision workbook link.