Active Safety Features: features that help protect the passengers in the event of crash.
ABS Brakes: these brakes stop the brakes from locking and the car from skidding. They transfer energy away from the passenger by getting hot.
Air Bags: these inflate on impact and slows the passenger's impact with the steering wheel. It increases the time it takes to change momentum and so decreases the force.
Seat Belts: these are slightly stretchy ans so increase the time it takes to change momentum and so decreases the force on the passenger.
Roll Cage: this is a rigid cage protecting the passenger.
Crumple Zone: this crumples in a crash transfering some of the energy in a shockwave, away from the passenger. It also increases the time, the car takes to stop and so decreases the rate of change of momentum, reducing the force on the passenger.
In a car crash there is a massive change of momentum: the car goes from travelling to stationary.
We can use ideas of forces, momentum and energy to protect passengers in the event of a car crash. We always want the passenger to experience less of a force. To do this we need to increase the time it takes for them to change momentum (or stop), or decrease the rate of change of momentum.
Passive Safety Features: these help prevent crashes
Lights: these help the driver see at night and the car be seen by other vehicles
Indicators: these alert other road uses to the drivers intensions
Brake Lights: these warn the vehicle behind you are stopping.
Reverse Lights: these warn people behind that the car is about to reverse
Mirrors: these allow the driver to see more of the road.
Breaks: these allow the driver to control the car's speed.
Steering Wheel: allows the driver to change the direction of the car
Examiners love looking at cars stopping because you can combine momentum questions about car safety with velocity-time or distance-time graphs.
Factors that increase thinking distance
Drugs and alcohol
Distractions such as music or passengers
Rain/snow might obstruct the view
Age decreases reaction time
Your stopping distance is the sum of the thinking distance-how far you travel while reacting- and the braking distance -how far you travel as the car slows down.
Stopping Distance = Thinking Distance + Braking Distance
Factors that increase braking distance