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Okay, lets begin!
|dw:1377641341636:dw| Now in any system in the universe, where there is potential energy(-U) it can do work and convert it to another form of energy and that PE becomes zero, (-U) = 0
In order to get that value back again. We need to apply +U right?
It's never possible to get from - to 0 to - again without the +.
Sure it is. A spring does that all the time.
A mass on a spring oscillates from high potential to zero back to high again without me doing any external work.
but that's impossible with gravity
A pendulum does exactly the same thing
You have a ball: |dw:1377641472701:dw| In order to get it back up that same amount of -mgh has to be applied.
Like with magnets(Im using this analogy since I understand the most) too, when attracted MPE = 0 Im doing + MPE(magnetic potential E) to separate them, but they get back to MPE due to -MPE.
MPE = 0*
That potential graph up there can explain the forces applied to a system as well.
You don't "do" energy. You do work. And the rest of that doesn't make sense.
Does it makes sense to define system based on energy? Or based on the work + force THEN the energy?
I mean, what comes first you know?
If that made any sense.
Force first, then energy.
not that it particularly matters.
Well I see that it does. Since we know energy is not of any Physical substance, but a major mathematical principle in Physics, I think it's more important to look at the forces first. Then the capacity of those force to do work, and what is doing work against it. Then define the energy, but I noticed a lot would just avoid dealing with force due to their complexity and just use the term: "It's Energy/ Energy this Energy that". I like to depend on things that we can understand test, see and feel like forces :)
This is my rant to Energy lol, I love it's importance. But I can't see it defining everything or explain everything, well maybe I am wrong! But thanks Joe anyways, I have a long way to go and a lot of studying!
Why do Physicists/Engineers love to explain everything using energy not forces? Maybe we will rely on it so much that it might be wrong sometime because we could not define a certain force and how it works on a system.
Because energy is far easier to deal with than forces are in almost all cases. In fact, there are some quantum mechanical effects that open the possibility that forces are NOT the most fundamental things, and that energy is more basic -- but that's a conversation for the far, far future.
What are those effects? I'd like to nibble into them!
You have a long way to go before it would even begin to make sense.
Indeed. But if forces are a key aspect in defining energy, and they might not fundamental in those effects, how is energy?
A conclusion one might draw from the effects I mentioned is that Energy is the most fundamental thing in the universe, and it gives rise to forces. We can only see and feel forces, so naturally when we developed our mathematical understanding of the universe we described forces first, then came to understand energy, which can be viewed as the underlying framework that dictates the forces.
In QM energy become even a more stronger principle i assume.
Yes, QM has to be formulated in terms of energy.
Yet, we can't fully define energy can we? I mean, its not something AS physical as forces. You said it gives rise to force, but how so? We could potentially have forces all around without energy being involved? Energy is a math born concept isn't it? How can we move it from being a tool to make things easier to explain and understand to a fundamental principle in Physics.
Why is it difficult to imagine that something that we thought was only mathematical at first turned out to be fundamental to physics?
I'm confused, because Forces being applied over distances can he explained and can be experimented, seen, created. But Energy, we can't explain it's origin in comparison to forces.
Sure we can. Energy is the thing whose slope gives the force. Easy peasy.
Energy is not a Substance of physical matter, yet can not be created or destroyed a number that is always the same in a system. I get confused, with that too!
It's a number that's always constant! :S
Energy is not a substance of physical matter, this is correct, and it is neither created nor destroyed. What's the problem?
AHA! So energy is a number, a number that measures the amount of work(Force x D) being applied in a certain system!
What? Where did that come from?
That's not right at all.
Than energy is what kind of a constant number?
It's not a number per se, it's a function whose value doesn't change. If x is your position, U is your potential energy, and v is your velocity, E(x,v) = 1/2 mv^2 + U(x)
And that function would depend on the system. I guess, we can build certain systems that gives different values of each variable in the function.
Energy is a function of the system, so there has to be a certain system, we must study it first then define it's energy! Not the other way around, that was my point and I think I've got it.