Final answer:
Seatbelts help protect passengers in a vehicle collision by extending the time over which the collision occurs, thereby reducing the impact force. This is based on the physics principle of impulse, which involves force and time.
Step-by-step explanation:
In the event of a crash or sudden stop, seatbelts may keep you from being thrown forward or striking the interior of the vehicle. This is due to the concept of impulse in physics, which explains how forces applied over a longer period of time result in a reduced impact force. Seatbelts, combined with other safety features like airbags, are designed to extend the time over which your body comes to a stop during a collision. This increased duration lowers the force you experience, reducing the likelihood of injuries such as fractures or ligament damage, which can occur under higher force impacts. The crumpling of a vehicle's frame also contributes to a longer collision time, further decreasing the force exerted on occupants.
Consider an example where a car crashes and stops in 0.26 seconds. If a passenger wearing a seatbelt has a mass of 70 kg and the car was initially moving at 10 m/s, the force exerted by the seatbelt can be calculated using the impulse-momentum theorem. This force is significantly less than what would be experienced without a seatbelt, demonstrating the seatbelt's role in passenger safety.