Science Forums 2

[TeleMad]

Because I was unsure, I asked at another board. Apparently no actual physicists responded, and there were replies that supported "yes" and some that supported "no".

Here's an idea I overlooked that might help. Consider the relative motion between the water and the rock from the point of view of stationary water and moving rock (Galileian relativity). Then we have the rock plowing through water molecules and pushing them out of the way. This would be in line with the rock having performed work on the water.

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I can imagine where the energy to do work - if such is being done - could be coming from. We would have to again look at the atomic scale where the force involved is the electrostatic force of electron shells in the water molecules and in the rock repelling each other when they come close enough to one another. Consider this again from the point of view of moving water and a stationary rock. The electrons of an approaching water molecule partially displace the electrons of the atoms in the rock's surface (that electron density can be redistributed by electrical forces is well known: an example is what occurs when you stick a balloon that has been rubbed against your hair to a wall. The negative charges on the balloon pushes the electrons in the atoms in the wall's surface towards the opposite side). This distortion of the electron distribution generates a sort of minute elastic potential energy, analogous to compressing a spring. As with a spring, the system restores itself to its original state, thereby returning the energy that was stored in it.