# kinetic energy in collisions

We were hoping you could help us understand collision energy. Vehicle A is driving West at 35mph and weighs 1437kg. Vehicle B is driving North at 35 mph and weighs 1882kg.
Vehicle B crashes into the side (frontal) of vehicle A. What is the amount of energy absorbed into Vehicle A? What is the difference in kinetic energy if vehicle A is stopped? Any help you could give us in understanding the physics of collisions would be wonderful.

What effect does it pose upon the engine compartment and components?

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A simple formula for energy absorbed by body/lost as heat in a collision is $\frac{1}{2}\muv_{rel}^2(1-e^2)$, where e is the coefficient of restitution, $\mu$ is the reduced mass ($\frac{m_1m_2}{m_1+m+2}$). But i think you're looking for something more complicated here. –  Manishearth Feb 17 '12 at 2:23
Remember energy is the area under the force-displacement curve. –  ja72 Feb 17 '12 at 6:39
The absorbed energy depends on a lot more variables than just velocity and mass. Some will be used up in friction, some in deforming the vehicles, the rest will go into the kinetic energy after the collision as the vehicles bounce off in different directions. It is easy though to calculate an upper limit: $E_{max} = E_{kinetic,A} + E_{kinetic,B}$. –  Alexander Feb 17 '12 at 19:44