Final answer:
Air bags are an integral safety feature that work in conjunction with seat belts to protect vehicle occupants in a collision, reducing the force on individuals by allowing it to be spread out over a longer time. They are not an alternative to seat belts but part of a comprehensive safety system in modern vehicles. Sitting too close to an airbag is dangerous due to the force of deployment, which is why it is recommended to sit at a safe distance.
Step-by-step explanation:
Air bags are a significant safety feature in vehicles designed to minimize serious injuries during a collision by allowing the net force on the occupants to act over a much longer time, resulting in less force on individuals. Airbags have been required on all passenger vehicles in the United States since 1991 and are commonplace in Europe and Asia. The rapid inflation of airbags is typically achieved through explosive chemical reactions such as the decomposition of sodium azide, which produces nitrogen gas to inflate the bag.
Seat belts are also crucial as they work in conjunction with airbags to provide safety. The presence of airbags does not replace the need for seat belts; rather, they work together to protect passengers.
It is dangerous to sit less than 25 centimetres away from the airbag unit in the steering wheel because the force of the deploying airbag can cause injury if one is too close. Therefore, the correct answer to the student's question is that air bags are dangerous if you are seated less than 25 centimetres away from the air bag unit in the steering wheel, but are an essential safety feature that works alongside seat belts to protect vehicle occupants.