Stopping distances

Question 1

What is stopping distance

Answer 1

driver perform an emergency stop, this is where maximum force applied by brakes to stop the car in shortest possible distance.
Longer it takes to perform emergency stop = higher risk of crashing

Question 2

How do you calculate distance it takes for a car to stop in an emergency?

Answer 2

Stopping distance = Thinking distance + braking distance

Question 3

What is the thinking distance ?
What is the braking distance ?

Answer 3

how far car travels during drivers reaction time
distance taken to stop under the braking forces

Question 4

Typical car braking distances

Answer 4

14m at 30 mph , 55m at 60 mph, 75m at 70mph

Question 5

What is thinking distance affected by ?

Answer 5

Your speed - Faster you’re going, further you’ll travel during the time you need to react
Your reaction time = longer -> longer thinking time

Question 6

What is braking distance affected by ?

Answer 6

Your speed - for given braking time, the faster a vehicle travels then longer it takes to stop

The weather or road surface = wet or icy, leaves or oil then less grip between tyres and road = which can cause tires to skid

Conditions of your tyres = tyres bald then they cannot get rid of water in wet conditions = leads them to skidding on top of the water

How good your brakes are = brakes worn or faulty = won’t be able to apply much force as well- maintained brakes = dangerous when you need to brake hard

Question 7

How do icy conditions affect safety

Answer 7

increase chance of skidding so driving too close to other cars is unsafe, longer thinking distance the more space you need to leave space in front of you in order to stop safely.
this is why speed limits are really important - affect stopping distance

Question 8

What occurs when the braking pedal is pushed ?

Answer 8

1) the braking pad presses onto the wheels, this causes friction and work is done between brakes and wheels from kinetic energy store of the wheels to the thermal energy store of the brakes, this causes the brakes temperature to increase

2) The faster a vehicle is going, more energy it has in kinetic store , the more work needed to be done to stop it. The greater the braking force for certain distances to stop it.

3) Large braking force = larger deceleration = dangerous as they can cause brakes to overheat or cause the vehicle to skid