Safety Features of Cars (WJEC GCSE Physics: Combined Science)

• Cars today are designed to rigorous safety standards to reduce the chance of a severe injury in the event of a collision
• In your exam you need to know about the following safety features built into cars:
  • Seat belts
  • Crumple zones
  • Airbags
• Each feature is designed to increase the distance over which the energy of the passenger is transferred
  • This reduces the impact force on the passengers and the severity of their injuries
• The force applied to a passenger in a collision can be calculated using a rearranged form of the work done equation:

• Where:
  • Force is the force applied to the passenger by the impact of the collision (N)
  • Work done is the work done by the safety device to reduce the movement of the passenger (J)
  • Distance is the distance moved by the passenger as a result of the collision (m)

Car Safety Features

The seat belt, airbag and crumple zones help reduce the risk of injury to a passenger by increasing the distance over which the collision takes place

• Seat belts
  • These are designed to stop a passenger from colliding with the interior of a vehicle by keeping them fixed to their seat in an abrupt stop
  • They are designed to stretch slightly to increase the distance the person moves in a collision
• Airbags
  • These are deployed at the front on the dashboard and steering wheel when a collision occurs
  • They act as a soft cushion to prevent injury on the passenger when they are thrown forward upon impact
• Crumple zones
  • These are designed into the exterior of vehicles
  • They are at the front and back and are designed to crush or crumple in a controlled way in a collision
  • This is why vehicles after a collision look more heavily damaged than expected, even for relatively small collisions
  • The crumple zones increase distance over which the collision takes place