Yes, high school stuff. Shame Jopo never got that far. Work=...

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03/06/20

18:27

Post #: 45016662
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Originally posted by tristanc ↑

Now, let’s go back (once again) to remedial high school physics to talk about this:

“Even silly people like many here must know what the S.I unit for gravity is "m/s 2" Study those units carefully.”

The units of the gravitational constant are indeed metres per second squared (m/s^2) - but those aren’t the units of work. Those are the units of acceleration.

Apply that acceleration to something with mass, and you get the units of kg.m/s^2 (otherwise known as the Newton, N). But that’s still not work - that’s a force. You could apply an infinite force to an immovable object for eternity and still have done exactly zero work (that is, expended zero energy).

In order to actually get work, the mass needs to move in the direction in which the force is being applied - yielding the units Newtons times metres (N.m, otherwise known as the Joule or J). While you’re sitting on the couch posting to HotCopper gravity is doing zero net work to you, and you’re doing zero net work against gravity.

Understand the above, and you’ll understand why the only way to get continuous heating from gravity is by continuous net movement towards the centre of gravity - that is, the Earth would need to be steadily shrinking over time. Pretty sure we would have noticed that by now.

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Yes, high school stuff. Shame Jopo never got that far.

Work= force x distance.

Great demo of adiabatic heating here.
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