Topic 2: Human Reaction Time

Question 1

What is human reaction time?

Answer 1

The delay between a human observing an event and acting

Question 2

What are the steps of the ruler drop experiment?

Answer 2

• someone holds a ruler just above your open hand
• they drop it at a random time
  Record the distance from the bottom of the ruler to the point where it was caught
• average this

Question 3

What is a vehicle stopping distance?

Answer 3

After seeing a hazard, before you react, during reaction time you travel X metres ( thinking distance) then you react causing the car to slow down and stop over Y metres (braking distance)

Question 4

What affects thinking distance?

Answer 4

• concentration
• tiredness
  -distractions
• influence of drugs/alcohol

Question 5

What affects braking distance?

Answer 5

• speed
• poor road conditions
• bald tires (low friction)
• worn brake pads
• mass (more passengers)

Question 6

What’s the rule of speed and braking distance?

Answer 6

The greater the speed the greater the distance travelled during the same time

Question 7

What is the danger of large decelerations (reductions of speed)?

Answer 7

When in a crash there is a large decelerations over very short time as you stop moving from a high speed: since force = mass x acceleration this large decelerations means a great force is exerted on the car and the passengers

Question 8

What is the danger of large decelerations in terms of momentum?

Answer 8

Before the crash you have a large momentum due to high velocity, after the crash you have no momentum as you aren’t moving: since force = momentum/time a great force is felt