Calculate Speed of Car in Car Accident

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SUMMARY

This discussion focuses on calculating the speed of a car involved in an accident using available data. The key figures include the distance from the point of impact to where the car stopped, the mass of both cars, and the final velocity of 0 m/s. Participants suggest using the equation vf² = vi² + 2ad to estimate the initial velocity (vi) if the acceleration can be determined from the force of impact using F = MA. However, the lack of skid marks and other variables complicates the accuracy of the estimate.

PREREQUISITES
  • Understanding of basic physics concepts such as force, mass, and acceleration.
  • Familiarity with kinematic equations, specifically vf² = vi² + 2ad.
  • Knowledge of how to calculate force using F = MA.
  • Awareness of factors affecting vehicle dynamics in collisions.
NEXT STEPS
  • Research how to apply the kinematic equation vf² = vi² + 2ad in real-world scenarios.
  • Learn about the methods police use to estimate vehicle speed from accident scenes.
  • Explore the principles of momentum conservation in vehicle collisions.
  • Investigate the role of skid marks in determining vehicle speed and stopping distance.
USEFUL FOR

This discussion is beneficial for accident reconstruction specialists, automotive engineers, and individuals interested in understanding vehicle dynamics during collisions.

gca114
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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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Too many unknown factors for getting an exact answer.

Some rough estimates can be possible.

Please search forum, this question is asked every few months.
 
gca114 said:
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.
 
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..
 
Well let's see. You can use the equation vf^2=vi^2 +2ad
you have vf, you say that you have distance, you don't 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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