Michael Rigby-Jones wrote:

>>> Only if you let go the stone, whereupon it's potential energy is
>>> converted into kinetic energy.  If you put the stone on a shelf it
>>> would stay there, and you don't have to provide power to a shelf do
>>> you?
>> 
>> But you have to provide force. Movement is not only about energy, it is
>> primarily about (resulting) force. 
> 
> Work = Force x Distance 
> 
> Remove either force or distance and work = 0.  There is no primary
> dependance on either force or motion. 

??? 

Distance is a consequence of motion. Motion (or its absence) is what
creates (or not) the distance. So if you are saying that distance = 0, you
assume that there is no movement. And that there is no resulting force. 

Energy changes are a consequence of movement, not a cause. It's the force
that causes the movement.

Gerhard

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