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Author Topic: If I give an object some potential energy, does its mass increase?  (Read 95360 times)

Offline Tintin_Triton

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So matter can basically be thought of as just potential energy because matter can be turned into energy and theoretically vice-versa, does that mean when I lift up a plate and increase it's potential energy, i've technically increased its mass?
The mass is increased, but not the mass of the plate: the mass of the system Earth-plate.

I think most of us may agree with this statement. I think he forgot to mention "Gravitational Potential Energy"

But I could never find a matching description or definition for potential energy. Is it always relative or inclusive for a system?
« Last Edit: 02/03/2010 08:27:08 by Tintin_Triton »
 

Offline VernonNemitz

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Geezer, I was under the impression that "shouting" in a message usually involves capital letters.  Meanwhile, italics is normally used to stress some part of a sentence, but with so many different fonts out there, it can be difficult sometimes to notice that some part of some text has been italicised.  So I like to add bolding to make sure it stands out.  My main beef with Farsight is not so much that there are problems with some of his ideas, so much as he appears to completely ignore any data that exposes those problems with his ideas.

...the rule of thumb is that the more mismatched the masses are, the more energy goes into the smaller mass.
Agreed, so long as we are talking only about the initial injection of kinetic energy into a system.  This has nothing to do with the process that converts kinetic energy, in a system, into potential energy, due to the influence of Gravitation or some other Natural Force.  And it is that conversion process, consistently for at least three of the four known Natural Forces (the Weak Force does not appear to either attract or repel), which can maintain mass ratios of the interacting bodies in the system.
 

Offline Geezer

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Vernon, you could try underlining instead. To me, bold has a connotation of loud, although it is, admittedly, not as loud as all caps.

Farsight, what do you think? You're on the receiving end.
 

Offline yor_on

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Potential energy is as simple as you want to make it. If you remember that it is a description of a relation between two objects, where your choice of objects always will be arbitrarily made, and that you simultaneously can have an arbitrary number of such relations relevant and valid for the same object  relative all other, you should be able to understand what it is.

It's not an 'energy' 'massed' at any specific point, it is an relation expressed when comparing two frames against each other. What you can talk about is expending energy, like acceleration. When you lift/move that plate you accelerate it, ever so little. When you after moving it f.ex place it on a table the movement/acceleration ends and you have an object at rest with the rest of its frame f.ex Earth. There is no new mass assembled in the object due to your moving it before. If the table dissolves and the object accelerate again, as observed/defined by an observer at rest with Earth, it will express an new relation with Earth as it meet it. That 'acceleration' is also a free fall where you could see it as that it's Earth coming to meet it. You can expend energy, like when lifting it against gravity, and you can define different relations (potential energy) for any object, be it at rest relative something or not, and that simultaneously, depending on your choice of comparison.

So either you will have to define potential 'whatever' energy as something not definable as a real sum as it will change depend on what you compare it too, or you will have to look at that plate reverently, understanding that in it it have all possible 'potential energies' there is, depending on your choice of comparison.

The third way is to pretend that 'potential energy' somehow becomes 'localized' by me when 'defining a system' which then seems to give the observer a Copernican outlook, not that surprising considering how short time we've been discussing 'relativity'.
« Last Edit: 04/03/2010 08:03:09 by yor_on »
 

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