Car Safety
Vehicle bumpers
Give way in low-speed impacts which helps increase impact time
This reduces impact force as it is spread out over a longer time period with same change in momentum
However for high speed collisions the force will be to great and the bumper/vehicle chassis will most likely become damaged
Crumple Zones
Engine compartment designed to give way when car collides head on
As the engine compartment crumples the impact time is increased and impact force is reduced, as same change in momentum as momentum is always conserved but greater time period
Seat-belts
Restrain person from colliding with dashboard or other part of the car if the car crashes or stops suddenly
The restraining force is less than the impact force would be so safer
The wearer is also stopped in a longer time frame, which means that the force on the pseron is less
Collapsible steering wheel
While the seatbelt is effective, if the driver makes contact with steering wheel can still do lot of damage
Collapsible steering wheel means that when the driver hits the wheel a lot of the force is used deforming the wheel, which reduces the force exerted by the wheel on the driver
Airbags
Reduces the force on person as the airbag acts like a cushion by increasing the impact time so reducing the force
Also, a greater contact area spreads the force out as surface area of airbag much greater than seatbelt - this reduces pressure on person
Also reduce the deceleration of the person - using F = ma as mass is constant this reduces the force
As in a crash all the kinetic energy is lost, without a seatbelt the kinetic energy of the person will be dissipated over much shorter distance and time period which greatly increases the force
Absorb energy during the crash to stop it being transferred to people within car, and also prevents direct deformation within the passenger cabin