Perpetual Motion

[LeedsRhinos]

Is the spinning of the earth an example of perpetual motion?

[Clanad]

Since the Earth's rotational period is slowing it doesn't appear so...

[jake-the-peg]

No, as Clanad says the Earth's rotation period is slowing.

In the Devonian period (400 million years ago) the day was 22 hours long.

We know this from studying fossil corals that lay down a daily growth ring

http://www.sepaq.com/pq/mig/miguasha/mig-en/a_ devonian_day.html

The main culprit in our Planet is the moon causing tides that lose energy through friction with the bottom of the sea.

In theory you can have perpetual motion in a totally isolated spinning system in space

"You can't have perpetual motion" is really just sloppy shorthand for saying you can't 'manufacture' energy.

[wildwood]

Here is proof that perpetual motion is very possible.

[ChuckFickens]

and next week we have an explanation of the dark suckerl theory!

[jno]

so, Jake, if there wasn't a moon, and the occasional asteroid hitting us, would we constitute such a system?

[rov1200]

It always amazes me whenever anyone mentions a use for perpetual motion they are classed as a crank. We know there are losses involved but its no reason not to take advantage of the remainder. For instance a flywheel has tremendous energy and when left to spin unaided, could produce enormous benefits. Magnetic motors also produce unseen energy but not infinitely so. Scientists have now patented a use for kinetic energy from rolling vehicles.
These square Earth troglodites should look positively at the world around us.

[Davethedog]

Rov1200 - all of your suggestions take energy. Every action has a reaction.

How does a fly wheel spin unaided? You find one and your in.

Square earth? No science

[rov1200]

Granted you need energy to start the flywheel turning but after doing its job all the energy left goes to waste. The same with rolling vehicles.

[Clanad]

The classical defintion of Perpetual Motion is "...The motion of some hypothetical device that continues forever with no obvious input of energy in violation of the laws of thermodynamics..." (This particular example derives from Wiktionary).

If one adheres to that palmary example, then, clearly, such a device cannot exist...
The Earth is subject to other gravitational forces in addition to those imposed by the Moon further decaying its movement.

[Davethedog]

That not in dispute.

But nothing is perpetual

[squarebear]

Only this discussion Dave.

[karatant]

No, I think the only example of perpetual motion is illustrated by a motion that has never had a start- anything having a start is assured of a stop ! Thereby blah blah blah ........................... there is no such thing, think about it, does that answer your question LeedsRhinos ?


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