What is thinking distance?

The time taken for a driver to react

What is the breaking distance?

The time taken for the brakes to make a car stop

How do you find the stopping distance?

Stopping distance = thinking distance + breaking distance

What happens to thinking distance when reaction time increases?

It increases

What can affect reaction times?

- being tired
- being ill
- taking drugs or alcohol

What does friction do to vehicles?

Slow them down

How do brakes stop cars?

They cause a lot of friction

What can affect the amount of friction created on a road?

The road being wet or having loose gravel

As the mass of a vehicle increases, what happens to the force needed to decelerate it?

It increases

What is momentum?

A measure of how strongly something is moving

What is the equation for calculating momentum?

Momentum(kg m/s) = mass(kg) x velocity (m/s)

What is a conservation of linear momentum?

When the total momentum of both objects is the same after the collision as before the collision

How do seat belts protect people during a car accident?

They stretch to reduce the change of momentum and it therefore reduces the force acting on the passenger

What are some benefits of air bags over seat belts?

They reduce momentum to zero more slowly and so prevent seat belt injuries

How do crumple zones help during car accidents?

These crumple in a specific way to reduce the momentum of the car over a longer period of time

How do you calculate force?

Force (N) = change in momentum (kg m/s) / time taken (s)

F= mv-mu / t

How do you calculate change in momentum?

Final velocity - initial velocity

mv-mu

What is work?

The amount of energy transferred

What is work measured in?

Joules (J)

How do you calculate the amount of work done?

Work = force x distance moved E = F x d

What is the equation for calculating power?

Power = work done / time taken P = E / t

How do you calculate the work done of stopping a car?

Breaking force x breaking distance

What is gravitational potential energy?

The energy that is stored because of an object’s position in a gravitational field

How do you calculate gravitational potential energy?

GPE(J) = mass(kg) x gravitational field strength(N/kg) x vertical height(m)

GPE = m x g x h

What is the equation for calculating kinetic energy?

KE (J) = 1/2 x mass(kg) x velocity^2

KE = 1/2 x m x v^2