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Is the transfer of energy instantaneous? Does energy act on a centre of mass?
Let's say there are two blocks on a frictionless surface. One is about to collide with the other stationary block in what will be an elastic collision.
When they collide, is the energy transfer from the moving to non-moving block instantaneous and will it concentrated in the non-moving block's centre of mass?
Sources are good.
1 Answer
- Andrew SmithLv 79 years agoFavorite Answer
No transfer of information is ever instantaneous.
We can treat it as instantaneous in some conditions. Where an object is quite "hard", the flexing of the surface is small and the energy transfer is rapid.
As long as the speed of collision is low compared to the speed of sound in the object then the energy transfer can be treated as effectively instantaneous.
Which means that the kinetic energy and the momentum is uniformly distributed through the whole body, yet it acts in a similar way to imagining the energy and momentum all located at the centre of mass.
But if the speed of the collision is high in comparison to the speed of sound in the object then we need a far more complex way of analyzing what will happen.
For example a bullet hitting a range of objects.
The momentum is not uniformly distributed and the object undergoes substantial deformation.
