[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 455

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Mathemat: A lot of bukafah. But curious, albeit pseudoscience.

Of course it's pseudoscience. A stool can stand on two legs. The moon can't fly away from the earth. It has enough 2 forces to stabilise its position while in 3 dimensional space: gravity and centrifugal force. Especially considering that the 2nd is directly proportional to the square of the distance from the Earth and the 1st is inversely proportional to it. Long live our Science.

 
Richie:

Of course it's pseudoscience. A stool can stand on two legs. The moon can't fly away from the Earth. It has enough 2 forces to keep it stable in 3 dimensional space: gravity and centrifugal force. Especially considering that the 2nd is directly proportional to the square of the distance from the Earth and the 1st is inversely proportional to it. Long live our Science.

What the hell, it is well known that there is exactly one force acting on the moon - the gravitational force, which is why it moves with acceleration - in full agreement with Newton's second law. Your so-called "centrifugal force" is a fiction that exists only in the non-inertial reference frame associated with the moon itself. It does NOT exist in the inertial system associated with the Earth.
 
alsu:
First of all, it's sarcasm and you don't get it. Secondly, you have it even cooler than the Academy of Sciences. For a body in 3-dimensional space to be in equilibrium, there must be at least 3 forces acting on it.
 
How can the moon be in equilibrium if, according to what is taught in schools, it is in a state of "stool with 2 legs"?
 
Richie:
For a body in 3-dimensional space to be in equilibrium, there must be at least 3 forces acting on it.

Wrong.

correction - at least 2 forces with opposite vectors.

 
sergeev:

err.

correction - at least 2 forces with opposite vectors.

Or none at all.
 
sergeev: Wrong. correction - at least 2 forces with opposite vectors.

Three. And all with opposite vectors - I agree. And with 2 in a steady state it won't.

Take 3 magnets. Two in your hands. The third is between them on the table. Will the 3rd be in stability with the other two approaching? No. It will "fall" either this way or that way :)

 
Richie:

Three. And all with opposite vectors - I agree. And with 2 in a steady state it won't.

Take 3 magnets. Two in your hands. The third is between them on a table. Will the 3rd be in a stable state when the other two are approaching? No. "It'll go either this way or that way :)

misconception.

You're confusing stable and unstable equilibrium.

 
sergeev:
Alexei, you are a smart man, can you explain to me why the Moon does not fall to Earth? For what reasons? At school I understood, but now I can't.
 
sergeev:

delusion.

you are confusing stable and unstable equilibrium.


Let me explain - if our three things are placed so that there are only attractive forces between the magnets, the equilibrium is stable, if there are repulsive forces, the equilibrium is unstable. But in both cases it is an equilibrium, but in the unstable version, a small deviation in the position of the magnets causes the equilibrium to be lost and the system flies out of it.
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