1.21 use the idea of momentum to explain safety features

1.21 use the idea of momentum to explain safety features

Objects in a car have mass, speed and direction. If the object, such as a person, is not secured in the car they will continue moving in the same direction (forward) with the same speed (the speed the car was going) when the car abruptly stops until a force acts on them.

Every object has momentum. Momentum is the product of a passenger’s mass and velocity (speed with a direction). In order to stop the passenger’s momentum they have to be acted on by a force. In some situations the passenger hits into the dashboard or windshield which acts as a force stopping them but injuring them at the same time.

Cars are now designed with various safety features that increase the time over which the car’s momentum changes in an accident. Crumple zones are one of the safety features now used in modern cars to protect the passengers in an accident. The car has a rigid passenger cell with crumple zones in front and behind. During a collusion, it creases the time during which the car is decelerating. This also reduce the force impacting on the passenger increasing their chances of survival.

Many cars are now fitted with air bags to reduce the forces acting on passengers during collisions again by extending the time of deceleration. Air bags are detected by devices called accelerometers that detect the rapid deceleration that occurs during a collision. The purpose of an airbag is to help the passenger in the car reduce their speed in collision without getting injured. An airbag provides a force over time. This is known as impulse. The more time the force has to act on the passenger to slow them down, the less damage caused to the passenger.