Why do they put tires next to racetracks as opposed to just fences?

I am doing a science project on impulses, and was wondering why they use tires. Of course if they put a wall that would just be dumb, so please answer semi-scientifically and not just "WELL THEN YOU WOOD DIE". Thanks!Why do they put tires next to racetracks as opposed to just fences?
They used to use fences in F1, but they stopped because in some types of accident the fence actually made things worse, not better. They were fine in head-on accidents, but when a car was sliding sideways they would cause the car to flip over on impact.
With regards to impulse it is important to remember that impulse is proportional to the average force, and if we assume that mass is constant the impulse is really proportional to the average acceleration. With impulse what you are essentially trying to study is the average force of the impact.

Take the first situation where you have a solid wall. For ease of intuition lets assume that the impact causes the car to stop instantly. Remember that average force: Favg = m(鈭唙/鈭唗) As t approaches 0 the average force approaches infinity (recall that average acceleration is equal to 鈭唙/鈭唗). Part of the function of the tyre wall is to increase the amount of time required for the impact. So for a given change in velocity the longer the amount of time taken the lower the average force.

This can be hidden somewhat by the impulse formula which cancels the time variables:

Impulse = Favg*鈭唗

= m(鈭唙/鈭唗)*鈭唗

= m鈭唙

Technically regardless of the time the reaction takes, the Impulse itself should be the same, however the decceleration the driver experiences can vary immensely depending on the time that the reaction takes. It could be the difference between a 50g stop and a 20g stop. Neither one is comfortable but you would be more likely to walk away from a 20g incident in an F1 car. There are also other advantages to tyre walls such as the energy dissipation and conservation of momentum.Why do they put tires next to racetracks as opposed to just fences?
The tyre wall or tyre barriers are there to absorb the impact and disperse the energy of the crash.



http://www.youtube.com/watch?v=PevE_Q7nS鈥?/a>





http://www.youtube.com/watch?v=kBqqJpI7k鈥?/a>
Tires are bouncy. Fences are not.Why do they put tires next to racetracks as opposed to just fences?
Tires absorb some of the impact, Like someone else has said and fences are harder and made of wire.
because the tire will absorb some of the impact and the fence will not
It helps to have the tyres nearby for the pit crew to change em, after all those 6 second pit stops might take a little longer if the tyres were in the next county. To my knowledge, fences have never been much help in the tyre changing process.
To protect the great Jenson Button when he crash into them. VIVA FORMULA BUTTON!

mr tire