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Perpetual motion!


bascule

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No, I'm claiming your interpretation of his law is flawed and incorrect.

 

How so? I understand his law to state that the a body in motion stays in motion unless something stops it. Does it say something else?

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How so? I understand his law to state that the a body in motion stays in motion unless something stops it. Does it say something else?

 

No, but it's a conditional statement. IF there is no external force. But there always is.

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No, but it's a conditional statement. IF there is no external force. But there always is.

 

I understand that and never said it didn't contain a condition. That doesn't change the fact that the law effectively says that motion would continue forever, perpetually, unless affected by an external force...

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I understand that and never said it didn't contain a condition. That doesn't change the fact that the law effectively says that motion would continue forever, perpetually, unless affected by an external force...

 

Unless affected by a nonzero external NET force, you mean?

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Read the newspaper story. It says he held the magnet in his hand.

 

“One of these days in your travels, a guy is going to come up to you and show you a nice brand-new deck of cards on which the seal is not yet broken, and this guy is going to offer to bet you that he can make the Jack of Spades jump out of the deck and squirt cider in your ear. But, son, do not bet this man, for as sure as you are standing there, you are going to end up with an earful of cider.” Damon Runyan in Guys and Dolls

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I understand that and never said it didn't contain a condition. That doesn't change the fact that the law effectively says that motion would continue forever, perpetually, unless affected by an external force...

 

So, perhaps we can say that this particular law can never be tested (proven nor disproven) since there's no such thing as an object in motion without the influence of a non-zero external net force.

 

Maybe it's more of a postulate than a law...

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I understand that and never said it didn't contain a condition. That doesn't change the fact that the law effectively says that motion would continue forever, perpetually, unless affected by an external force...

 

Yes, but that's still not really the same as saying all motion is perpetual — that's not the context of the law. It affirms that motion stopping (or increasing) is due to external influences, and is not an intrinsic property.

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So, perhaps we can say that this particular law can never be tested (proven nor disproven) since there's no such thing as an object in motion without the influence of a non-zero external net force.

 

Maybe it's more of a postulate than a law...

 

It can be tested if you calculate what that external force is.

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It can be tested if you calculate what that external force is.

 

I still haven't finished my first cup of coffee, so I'm a bit slow presently, but I don't follow your point.

 

How would calculating the external force allow us to test empirically that... without that external force... an object would forever stay in motion?

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I still haven't finished my first cup of coffee, so I'm a bit slow presently, but I don't follow your point.

 

How would calculating the external force allow us to test empirically that... without that external force... an object would forever stay in motion?

 

Anotehr way of looking at it is, without an outside force an object will never move...

 

The point of this law was NOTHING to do with perpetual motion, but was to show that motion is not an intrinsic property of objects.

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Anotehr way of looking at it is, without an outside force an object will never move...

 

The point of this law was NOTHING to do with perpetual motion, but was to show that motion is not an intrinsic property of objects.

 

That would seem to imply that the state of a body, inertia, at motion or rest, is an intrinsic property of matter....

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I'm still of the school that perpetual motion only qualifies as such if it can be placed in a zero g space and it continues to run without fuel. Anything here on the planet would either require gravity to work or would run in spite of it.

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I'm still of the school that perpetual motion only qualifies as such if it can be placed in a zero g space and it continues to run without fuel. Anything here on the planet would either require gravity to work or would run in spite of it.

 

As was pointed out earlier in the thread, even objects in outer space are subject to friction and other forces.

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