Crumple zones Flashcards
Equation for momentum
momentum = mass × velocity
what does a sudden change in momentum, in a
collision result in?
a large force that can cause injury
Describe the typical safety features of modern cars
that require energy to be absorbed when vehicles
stop:
• heating in brakes, crumple zones, seatbelts,
airbags.
Explain why seatbelts have to be replaced after a
crash
they can be damaged by the force of a body against them
Recognise the risks and benefits arising from the use
of seatbelts.
+ reduces potential injury
- passenger might be trapped in a car by their seat belt after an accident and not be able to get out
How can the stopping forces experienced by the people in the car in a collision be reduced by?
- increasing stopping or collision time
- increasing stopping or collision distance
- decreasing acceleration.
Describe how seatbelts, crumple zones and airbags are useful in a crash because they: • change shape • absorb energy • reduce injuries.
They all change shape on impact to absorb energy and therefore reduce the risk of injury to the people in the car also lengthen the time that the passenger takes to stop. This means that a passenger’s momentum changes over a longer time so they experience less force and suffer fewer injuries.
equation for force
force = change in momentum / time
Describe how test data may be gathered and used to
identify and develop safety features for cars.
They can be observed during a controlled crash so can identify how the worst injuries happen. This allows manufacturers to include improved safety features.
Explain how spreading the change in momentum
over a longer time reduces the likelihood of injury
Crumple zones, seat belts and airbags means that a passenger’s momentum changes over a longer time so they experience less force and suffer fewer injuries.
Analyse personal and social choices in terms of risk
and benefits of wearing seatbelts.
wearing a seat belt in the UK is compulsory in both the front and back seats. This law was brought in to protect people from injuries and to reduce the cost to the National Health Service of treating people after car accidents.
Describe how ABS brakes:
• make it possible to keep control of the steering
of a vehicle in hazardous situations (e.g. when
braking hard or going into a skid)
• work by the brakes automatically pumping on and
off to avoid skidding
• sometimes reduce braking distances.
They prevent the tyres from skidding during heavy breaking pumping on and off rather than holding the wheel tight. This increases the area of the tyres in contact with the road and gives the driver better control of the car. This often reduces the overall breaking distance.
