Question

@Jemurray3

Answer 1

Okay, lets begin!

Answer 2

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

Answer 3

In order to get that value back again. We need to apply +U right?

Answer 4

It's never possible to get from - to 0 to - again without the +.

Answer 5

Like gravity.

Answer 6

Sure it is. A spring does that all the time.

Answer 7

A mass on a spring oscillates from high potential to zero back to high again without me doing any external work.

Answer 8

WAH!

Answer 9

but that's impossible with gravity

Answer 10

A pendulum does exactly the same thing

Answer 11

You have a ball:


In order to get it back up that same amount of -mgh has to be applied.

Answer 12

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.

Answer 13

MPE = 0*

Answer 14

That potential graph up there can explain the forces applied to a system as well.

Answer 15

You don't "do" energy. You do work. And the rest of that doesn't make sense.

Answer 16

Does it makes sense to define system based on energy?
Or based on the work + force THEN the energy?

Answer 17

I mean, what comes first you know?

Answer 18

If that made any sense.

Answer 19

Force first, then energy.

Answer 20

not that it particularly matters.

Answer 21

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 :)

Answer 22

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!

Answer 23

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.

Answer 24

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.

Answer 25

What are those effects?
I'd like to nibble into them!

Answer 26

You have a long way to go before it would even begin to make sense.

Answer 27

Indeed.
But if forces are a key aspect in defining energy, and they might not fundamental in those effects, how is energy?

Answer 28

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.

Answer 29

In QM energy become even a more stronger principle i assume.

Answer 30

became*

Answer 31

Yes, QM has to be formulated in terms of energy.

Answer 32

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.

Answer 33

Why is it difficult to imagine that something that we thought was only mathematical at first turned out to be fundamental to physics?

Answer 34

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.

Answer 35

Sure we can. Energy is the thing whose slope gives the force. Easy peasy.

Answer 36

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!

Answer 37

It's a number that's always constant! :S

Answer 38

Energy is not a substance of physical matter, this is correct, and it is neither created nor destroyed. What's the problem?

Answer 39

AHA!
So energy is a number, a number that measures the amount of work(Force x D) being applied in a certain system!

Answer 40

What? Where did that come from?

Answer 41

That's not right at all.

Answer 42

Than energy is what kind of a constant number?

Answer 43

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)

Answer 44

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.

Answer 45

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.