stopping distances

• What is the stopping distance of a car?

  The total distance to stop in an emergency
• How is stopping distance calculated?

  Stopping distance = Thinking distance + Braking distance
• What is thinking distance?

  Distance travelled during reaction time
• What is braking distance?

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

  Greater speed results in greater stopping distance
• If a vehicle's stopping distance is 40 m and thinking distance is 14 m, what is the braking distance?

  26 m
• What is the relationship between force and deceleration according to Newton's Second Law?

  Force equals mass times acceleration
• What does the equation F = ma represent?

  Force, mass, and acceleration relationship
• What happens to brakes when they overheat?

  They can fail and become ineffective
• What is the effect of deceleration on passengers in a vehicle?

  Passengers experience deceleration and potential injury
• How do you estimate the acceleration of a car that stops in 0.1 seconds from 20 m/s?

  Acceleration is approximately $-200 \text{ m/s}^2$
• What is the force on a 70 kg passenger decelerating at $-200 \text{ m/s}^2$?


  Force is approximately $-14,000 \text{ N}$
• What is reaction time?

  Time between seeing and reacting to something
• What is the typical human reaction time range?

  0.2 to 0.9 seconds
• How can you measure human reaction time using a ruler?

  Catch a falling ruler to measure distance
• What factors affect braking distance?

  Speed, vehicle condition, road condition, mass
• How does speed affect braking distance?

  Higher speed increases braking distance
• What is the relationship between kinetic energy and braking distance?

  Braking distance is proportional to kinetic energy
• What is the formula for kinetic energy?

  $KE =$$\frac{1}{2}mv^2$
• How does doubling the velocity affect braking distance?

  Braking distance increases by four times
• What is thinking distance?

  Distance from realizing to applying brakes
• What factors can increase thinking distance?

  Tiredness, distractions, intoxication
• How does a tired driver's reaction time compare to an alert driver?

  A tired driver has a greater reaction time
• What are the main factors affecting braking distance?

  • Speed of the vehicle
  • Vehicle condition (e.g., worn tyres)
  • Road condition (e.g., wet or icy)
  • Vehicle mass (e.g., heavier vehicles take longer to stop)
• What are the main factors affecting thinking distance?

  • Speed of the vehicle
  • Tiredness
  • Distractions (e.g., mobile phone use)
  • Intoxication (e.g., alcohol or drugs)
• What is the relationship between thinking distance and speed based on the graph?

  • Thinking distance is directly proportional to speed
  • Doubling speed doubles thinking distance
• What happens to the braking distance when the speed of a vehicle increases?

  • Braking distance increases significantly
  • It is proportional to the square of the speed
• What is the significance of the negative value in resultant force during deceleration?

  • Indicates force opposes motion
  • Represents deceleration of the object