Head Restraint
Purpose during a crash:
During a crash a head restraint limits head movement, thus reducing the probability of the passenger acquiring whiplash, a type of neck or spinal injury. Whiplash is when a car is hit in the rear and pushed forward, the car seat pushes the passenger forward (force = mass times acceleration). The passenger’s head will lag behind the torso (example of inertia), causing hyperextension, which is when the neck bends back and stretches. It is not life threatening however it can cause pain and may affect the brain due to being shaken around inside the skull. |
Physics:
During a crash the car stops almost instantly, however the passenger will keep moving forward at a constant velocity until a force stops them. Newton’s first law, that an object at rest will stay at rest and an object in motion will remain in motion, supports this. Airbags decrease the probability that the passenger will be injured by providing a flat object that will not bend the passenger's neck or spine at a dangerous angle.
During a crash the car stops almost instantly, however the passenger will keep moving forward at a constant velocity until a force stops them. Newton’s first law, that an object at rest will stay at rest and an object in motion will remain in motion, supports this. Airbags decrease the probability that the passenger will be injured by providing a flat object that will not bend the passenger's neck or spine at a dangerous angle.
Developments:
1921: Benjamin Katz invents the world's first head restraint for cars
1950s and 60s: Motor vehicle manufactures, safety research institutions and the medical community devise head restraints.
1969: Head restraints are mandated for the front seats.
1995: A very low, three, percent of head restraints are rated to be affective.
September 2010: Measurements for head restraints are standardised. A minimum of 74.93cm from an occupant's hip to the top of a head restraint is required and a backset of 5.588cm or less.
1921: Benjamin Katz invents the world's first head restraint for cars
1950s and 60s: Motor vehicle manufactures, safety research institutions and the medical community devise head restraints.
1969: Head restraints are mandated for the front seats.
1995: A very low, three, percent of head restraints are rated to be affective.
September 2010: Measurements for head restraints are standardised. A minimum of 74.93cm from an occupant's hip to the top of a head restraint is required and a backset of 5.588cm or less.