Conservation of momentum
Definition
In a collision, the vector sum of all momenta (mass × velocity) before impact equals the vector sum after, provided no significant external forces act during the brief impact interval. This is the central equation in multi-vehicle reconstruction.
Related terms
- Coefficient of friction (mu)
- The dimensionless ratio of frictional force to normal force between tire and road. It determines how quickly a skidding vehicle decelerates. Typical...
- Critical speed yaw mark
- Curved scuff marks deposited when a vehicle slides sideways. The radius of curvature and friction coefficient yield the vehicle's minimum speed at...
- Delta-V
- The change in vehicle velocity during the crash event, recorded by the EDR as a time-history. It is the integral of the...
- Perception-reaction time (PRT)
- The elapsed time from when a driver can first perceive a hazard to when the brakes begin to apply. Olson and Farber...
- Skid mark
- A dark rubber deposit left when locked wheels slide along the road surface. Length combined with the friction coefficient allows calculation of...
Explained in
- Accident Reconstruction PhysicsIn a collision, the vector sum of all momenta (mass × velocity) before impact equals the vector sum after, provided no significant external forces act during t...