Momentum Flashcards
Stopping distance
The total distance travelled from when the driver spots an obstruction to when the car actually stops
What makes up the stopping distance?
2 parts
Thinking distance
Braking distance
Thinking distance
Distance travelled by the car before they have time to react to the obstruction
Aka during the reaction time
Braking distance
Distance the car travels to when they apply the brakes to when the car actually stops
What happens to the stopping distance if the vehicle speed is high?
It will be bigger
Aka it will drive a longer distance between the driver noticing the obstruction and the car actually being stopped
Which is BADDDDDDDDD
What affects the thinking distance?
A long reaction time
If you are tired
Alcohol
Drugs
Caffeine
Old
Distractions
What affects the braking distance?
Wet/icy conditions = less friction = more slippery = longer braking distance
Worn tyres also reduce friction
Worn brakes
Kinetic energy equation
1/2 x mass x velocity^2
What happens to the kinetic energy if you double the velocity?
You quadruple it because in the equation velocity is squared
What happens to kinetic energy stores when a car brakes?
All kinetic energy is converted to other forms of energy
Because it stops moving
What happens during braking?
The brake presses against the wheel
Force of friction acts between brake and wheel
So kinetic energy of the car is converted to thermal energy in brakes
So temperature increases
And car slows down = loses kinetic energy
How does speed affect braking distance?
Greater speed = needs greater braking force to stop the car for a shorter distance
What happens if the driver brakes very forcefully
The car decelerates rapidly
Because large amounts of kinetic energy transferred to thermal in brakes
So brakes overheat
And driver may lose control over vehicle
Force that acts between brakes and wheel of the car
Friction
