Gravitational / Magnetic Potential Energy Question

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Discussion Overview

The discussion centers around the concepts of gravitational potential energy and the implications of objects appearing in gravitational fields without prior energy input. Participants explore hypothetical scenarios involving objects like baseballs and the effects of gravity on them, as well as the broader implications of energy conservation in these contexts.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether an object that "magically" appears in the air would fall, suggesting that energy input is typically required to lift objects against gravity.
  • Another participant argues that a magical appearance would violate conservation of energy, asserting that the object would still be influenced by gravity unless the magic disrupted that force.
  • A subsequent participant proposes a scenario where a baseball is placed at a height similar to satellites, asking if it would fall due to gravitational influence or remain stationary without prior energy input.
  • Another participant states that the baseball would possess potential energy due to its position in the gravitational field, which is linked to the energy required to lift it there.
  • A further hypothetical is introduced regarding an "alien baseball" that comes from deep space, questioning its potential energy status upon entering Earth's gravitational field.
  • One participant asserts that the alien baseball would have potential energy simply because it is within the gravitational field.
  • Another participant discusses the implications of gravitational potential energy in relation to meteorites falling to a planet, suggesting that the process increases thermal energy and raises questions about the conservation of energy and gravitational field strength.

Areas of Agreement / Disagreement

Participants express differing views on the implications of objects appearing in gravitational fields and the nature of potential energy, indicating that multiple competing views remain without a consensus.

Contextual Notes

The discussion involves assumptions about energy conservation and the effects of gravitational fields, which may not be fully resolved or universally accepted among participants.

RestlessMind
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To get energy out of an object falling down to Earth or a magnet slamming into another one, you have to lift the object up or pull the one magnet away from the other, which makes sense with Newton's laws.

I was wondering, if an object just "magically" appeared out of nowhere in the air without anyone lifting it up first, would it fall down? After all, nobody put any energy into lifting it up.

Thanks, and sorry if this seems like a silly question, lol.
 
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The problem with these types of questions is that if you presume magic, then you can conclude any thing you want. That is, there can be no conclusion from a nonsensical premise.

If you want something to magically appear, then that would violate conservation of energy. After it appeared then it would still be influenced by the gravitational field, unless the magic somehow disrupted that. :)
 
Haha, you're right I suppose!

How about a situation in which a baseball is placed steadily, unmoving, about as far from the Earth as common man-made satellites. Disregard the motion of the Earth and Moon. Would the baseball fall to earth, being well within its gravitational field? Or would it simply stay stationary regardless, because it received no potential energy like a baseball launched up there would get from being lifted up?
 
The baseball would have potential energy by virtue of being at a particular position in the gravitational field. This potential energy would (in part) come from the energy it takes to lift it there.
 
But what if it came from space? I mean, to be realistic, what if it was an alien baseball? Lol, I can't think of anything else. Basically I mean, what if it came from deep space and just was placed in the Earth's gravitational field? It didn't come from Earth. What then?
 
Then it has potential energy due to it being in a gravitational field.
 
I see, thanks for the answers!
 
I have been thinking about that for a while though ..

the gravitational potential is directly proportional to the mass of the two involved objects, if a planet kept attracting meteorites for example, they will gain kinetic energy as they fall, as soon as the hit the surface thermal energy will be released, AND the total mass of the planet will increase too, so the gravitational potential will increase and other meteorites get attracted and so on ..

so the result is an increase in thermal energy, that can escape the planet in the form of radiation, without a decrease in the field strength, which seems controversial for me.
 

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