Where does collision energy go?

General Crash Reconstruction Tecnhiques
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brian
Posts: 499
Joined: Tue Jul 14, 2009 10:52 am

Where does collision energy go?

Post by brian »

June 3, 2010: Q (rcd via email): In vehicle accidents, we mention about the 'energy loss'. There is a initial energy that is about the initial speeds and final energy that is about the final speeds. And there is an energy loss of the system. But, what happens to the loss energy because we know that energy never get lost but turn into another form of energy. For ex: An accident occurs and 10.000 J enegy is lost. Can we say that 10.000 J heat energy occurs in this accident?
A: When vehicles collide work is done in deforming the structures of each vehicle. The 'energy lost' in not actually lost, it is used in the collision to bend and crush the vehicle structure. Obviously since it is not bending and crushing the vehicle to a usable shape then it is considered 'lost'.
If the vehicles were elastic then the work energy of deformation would be restored as the deformed vehicles reform their original shapes. Some collision deformation energy is converted to heat during the bending and deforming of the vehicle structure and some heat also is created as the tires and other vehicle components interact with the ground (either roadway or other surface on which the collision occurs).
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