Originally Posted by galexander
Okay JazzRoc if work is not being done by the solidity of the Earth's surface against the solid rock then what about the following example?
Try holding a heavy sack of potatoes at arms length with just the one arm held horizontally. Hard WORK
isn't it? And yet according to your logic no work is being done because the sack is stationary!
Ah. I see where you're coming from.
Of course it's work for a human arm. A constant stream of work is being done maintaining muscular tension. That you might call STRAIN
. But muscles work by electrochemical pressure, and their electrical "circuits" are very lossy. A constant stream of ATP (the body's gasoline) is required to maintain each muscular fibre's position. It gets "burnt" to lactic acid which is flushed to the kidneys.
But consider a rock on a plain on the Moon.
An old BIG rock which might have whacked down in an aftermath of an early asteroid strike and would have sat there for a million years. Straining. Consuming nothing. You need to understand the difference between plasticity and elasticity as well, by the sound of it.
Has it done a virtually infinite amount of work?
Or the Earth? The whole of it is in strain searching to fall to the centre. An almost infinite amount of work?
No. Work is done raising up a weight up using a pulley. Or the same amount of work done when it is released and falls back to where it was lifted from. Technically described as accelerating a mass over a period of time, and thus involving the dimension of length. In free fall the acceleration will be the local gravitational constant for the gravitational body. The product of the particular mass of that body, the acceleration, and the distance travelled will determine the work done.
In deep space, the acceleration will be determined by the mass divided by the force. The work done (say by a rocket engine) would then be the mass times times acceleration times distance the rocket engine works over.
Get your head round it. Pick up a schoolbook on mechanics and read and understand it.
Again I had to re-edit my work: I really must pick up a physics book again.