# Car Accident Question

#### gca114

Recently I have been involved in a car accident, and would like to figure out what was the speed of the other car that crashed into us.

I only have two figures, the distance from the point of impact to where the car stopped and the mass (of both cars); and also, the final velocity which is 0 m/s.

Does someone think that this is possible to figure the speed of the other car that crashed into us?

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#### Borek

Mentor
Too many unknown factors for getting an exact answer.

Some rough estimates can be possible.

#### BruceW

Homework Helper
Recently I have been involved in a car accident, and would like to figure out what was the speed of the other car that crashed into us.

I only have two figures, the distance from the point of impact to where the car stopped and the mass (of both cars); and also, the final velocity which is 0 m/s.

Does someone think that this is possible to figure the speed of the other car that crashed into us?
I think the police use the skidmarks of the tyres to work out the speed at which the car was travelling. And other stuff. They probably have the best estimate of anyone.

#### gca114

There were no skidmarks.. as there was not a chance for breaks.. also.. it wasn't a collision crash... both cars separated from each other after the crash..

#### spuding102

Well lets see. You can use the equation vf^2=vi^2 +2ad
you have vf, you say that you have distance, you dont have acceleration but if you knew with how much force the car hit you with you can figure out accelartion from F=MA and then you can find Vi. Therefor if you can figure out the force of impact it can be done. This of course would be an estimate as some other factors are involved.

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