Seatbelts

Seatbelts

Blake Smith

When travelling at slow speeds in your car the wearing of a seatbelt has little effect of your body when you brake. So why is it important to wear your seat belt?

A driver or passenger travelling in a car is moving at the same speed as the car. If the car suddenly stops, the body of the rider inside will keep moving forward at the same speed. This demonstrates inertia. The tendency of a moving object to keep moving, or of a stationary object to remain at rest. Basically Newtons first law; that a body stationary or moving with constant velocity will want to continue to do so, unless acted on by a force.

Lets understand what is happening here. First drive along in your car at 60 km/h on a backstreet with no traffic, then brake gently and slowly. You will notice that the seat belt doesn’t really do much to hold your body. Now do the same again but this time break as quickly and sharply as you can. Your body will be thrown forwards with great force, and your seatbelt will be literally holding you in place.

Now your body was what is commonly referred to as being "thrown forwards", however this is not the case. Your body was actually not slowing down much at all and your velocity relative to the car initially was much greater. The car began to slow down due to breaking and your body in accordance with Newtons First law wanted to continue to move at the original constant velocity. Now if your seat belt was not there to provide an opposing force, to your...

Seatbelts

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