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Re: [Phys-l] Conservation of energy in nuclear reactions




Consider an astronaut dropping a rock on the moon. While the rock is
falling, how does the kinetic energy of the moon/rock/astronaut SYSTEM change?
How does the rest energy of the moon/rock/astronaut SYSTEM change?
Before the drop:
System potential energy = some negative value a
System kinetic energy = zero

During the drop:
System potential energy < a
System kinetic energy > 0

After the drop:
System potential energy << a
System kinetic energy = 0

Are there other forms of energy that are changing?
Yes.

Brian W

Ah, I see I left the fate of the energy loss hanging.
Perhaps I thought it was so obvious that it's hard to believe there could
ever be a question about it.

A rock that impacts the Moon's surface transfers energy to heating of the surrounding surface, and as a traveling vibration wave. Both of these modalities end in radiating energy into space - out of the system boundary.

:-)

Brian W