the moon slowing down

[Souron]

Irregardless of if a force is applied instantaneously or gradually, if that force is consistently opposite the moon's direction, it will reduce the distance of the moon.

I don't doubt that the moon is moving away and slowing down on it's own accord, because of the nature of it's orbit. But that is not an external force; the moon is trading kinetic energy for potential.

 

[History_Buff]

I'm not talking about planes and orbits, I'm talking about gravity. And possibly magnetics.

You're going to have to explain. The gravitational effect of the moon is not what gives Earth it's axial tilt, and it wouldn't change it either short of a collision.

 

[History_Buff]

Irregardless of if a force is applied instantaneously or gradually, if that force is consistently opposite the moon's direction, it will reduce the distance of the moon.

I don't doubt that the moon is moving away and slowing down on it's own accord, because of the nature of it's orbit. But that is not an external force; the moon is trading kinetic energy for potential.

The reason the moon is moving away is not because of it's orbit, it's because of tidal forces here on Earth.

 

[cardgame]

Perhaps... I should have put this in quotes.

The Earth's tilt would vary between 0 and 90 degrees

The History Channel is usually a very reliable source if it's not talking about ghosts, UFOs and Monsterquest crap.

 

[History_Buff]

Perhaps, it wouldn't be the first thing they've bungled. Do you happen to recall the name of the program? I want to watch it now.

 

[Perfection]

Irregardless of if a force is applied instantaneously or gradually, if that force is consistently opposite the moon's direction, it will reduce the distance of the moon.

Right, but the question wasn't about force, it was about speed. A quick slowdown of the moon is different than a gradual slowdown.

 

[cardgame]

Perhaps, it wouldn't be the first thing they've bungled. Do you happen to recall the name of the program? I want to watch it now.

It was just called The Universe... and there are lots of those that are not about the moon. So.. good luck

 

[Perfection]

If an object is orbiting another and slows down, then it will start to get closer to it. This is simply because it is accelerating towards it faster than it is moving around it and so it starts to spiral inwards, eventualy reaching equilibrium when it gets close enough, or crashing. I dont see how a slow or gradual change makes any difference.

I think you might be confused with the reverse phenomenon. An object moved away from the earth will lose speed as it is doing work against gravity. This does not imply that an object losing speed will move away from the earth.

Let me clarify. The language here is a bit maddening. There are two possible (actually more, but let's go with the simplification), ways that a force could be applied to the moon: it can be with its motion or against it.

If the force applied to the moon is against its motion, we might well see a short-term slowing of the moon, but in the long run the moon will be going faster. (I called this the "sudden" slowdown)

If the force applied to the moon is with its motion, we might well see a short-term speed-up of the moon, but in the long run the moon will be going slower. (I called this the "gradual" slowdown)

In both scenarios the moon slows down at least some of the time.

So in a certain sense this debate is about which scenario is more fitting with the OP's statement (an argument I find boring). My objection is not really to those who think the short-term slowdown is more appropriate then the long-term I immediately thought of, but those who have actual physical untruths in their statements (like those who say that the moon isn't in general slowing down).

I hope that clarified everything. Any questions?

 

[Souron]

Right, but the question wasn't about force, it was about speed. A quick slowdown of the moon is different than a gradual slowdown.

No it isn't. To slow down the moon quickly you have to apply a force quickly in the direction opposite it's motion. To slow down the moon gradually, you apply a gradual force. Either way, the orbit decreases.

Or you can leave the moon to it's own devices, which happens to be invoke a gradual slowdown. But there is nothing special about this slowdown being graual. The rate at which it slows down is insidental.

 

[Perfection]

I think my above post adequately covers your objection. (quick is the same as sudden).


Temporary/Permanent might have been better labels for the two scenarios.

 

[Agent327]

Just reposting this minor detail:

Lets not forget that the Moon is moving away from the earth... About 3 centimeters a year.

Better worry what the ultimate effect of this will be.