Re: COLLISION

[Leigh Palmer <palmer@SFU.CA>]

> When a moving railroad car collides with a stationary car of equal mass
> elastically, the one car stops and the other begins moving with the same
> velocity as the first.
>
> If they now collide inelastic ally by coupling together, half of the
> kinetic energy of the system is lost.
>
> Now, my concern is, where has the kinetic energy 'gone'? Certainly air
> was moved, sound was created and deformations took place but surely all
> this happened in the elastic collision too.
>
> Why should there be such a significant difference in the accounting of
> energy between these two systems?
>
> Any help would be appreciated.

Most of it can be found if one carefully measures the temperatures
of all the components of the system before and after the collision.
The energy (including the internal energy of the system) is conserved;
the mechanical energy is not conserved.

Leigh