Topic 5 Stopping Distances Flashcards
What is an emergency stop
When the Maximum force is applied to in the brakes in order to stop the car in the shortest possible distance
What does the longer it takes to do an emergency stop mean
The higher the risk of crashing
Stopping distance =
Braking distance + thinking distance
What is thinking distance
How far a car travels during the drivers reaction time
What is the drivers reaction time
What time between the drive a seeing a hazard and applying the brakes
What is braking distance
Distance to take you to stop under the braking force once the brakes are applied
Typical car breaking point
40 m at 30 mph
55 m at 60 mph
75 m at 70 mph
What is thinking thinking distance affected by
Speed- the faster you travel the further you’ll travel during the time you react
Reaction time- the longer your reaction time the longer your thinking distance
What is braking distance effected by
Speed- for given braking distance the faster a vehicle travels the longer it takes to stop
Weather or road surface- if it is wet or icy are there are leaves or oil on the road there is less grip so less friction between the vehicles tires and the road causing them to skid
Condition of tyres- bald tyres (don’t have any tread left) cannot get rid of water in wet conditions which leads them skidding on top of water
Condition of brakes- if worn or faulty they won’t be able to apply as much force as well maintained brake
What happens if you have a longer stopping distance
Give more space you need from other cars in order to be safe
What happens when brake peddle is pushed
Brake pads pressed onto the wheels causing friction which causes work to be done between the brakes and the wheels transferring energy from the kinetic stored of the wheels to the thermal energy store of the brakes amd increase the temperature
The faster a vehicle is going the more energy it has in its kinetic energy store so
More work needs to be done to stop it so a larger deceleration is needed to stop it within a certain distance
What does a larger braking force mean
Larger deceleration
Why can large deceleration be dangerous
May cause brakes to overheat so won’t work as well or could cause vehicle to skid
