Work equation?

urtalkinstupid

Yes, you are right; I do know that force does not equal energy, but force is related to energy. In order for a force to be applied, there is a needed energy source.

Has my question been answered? No.

Since when did you refer to gravity making things push? I think it should be the ground is pulling the fridge, and the fridge is pulling the ground. Yea, doesn't make much sense putting it in the pull form. So, you are saying that magnets are conductors for gravitational fields? One problem I see in this. If gravity is lending this force, it's basically unlimited, because that magnet sits there until a force is pulling it away. This "unlimited" amount of force this gravity is providing in order ot keep the net force 0 requires an energy source of unlimited energy, seeing that force is related to energy. This energy seems as though it is created on the spot as a constant supply to the magnet.

Give me your arguement on this so I can improvise mine. I'm not able to make a direct arguement based on what you have wrote, yet. So, I'm waiting. I have to go somewhere right now, so if I don't reply, don't think it's because I don't have a plausible answer.

urtalkinstupid

Nereid, everyone is entitled to their own opinion. Whether it be right or wrong.

Alkatran

You don't need a change in energy for a force, because two forces can cancel each other out (so no energy change). Perhaps an energy source, I don't really know, above my level.


Has my question been answered? No.


Gravity is pulling the fridge into the ground, so the fridge is pushed/pulled against the ground, and the ground is pushing back. THEY'RE JUST WORDS.

AKA I can't come up with something to argue about.

Tom Mattson

Yes, but there is no entitlement to waste bandwidth at this (privately owned) website. When I locked that other thread and advised you all that PF is not a chatroom for children, I was specifically thinking of both yourself and beatrix kiddo.

chroot

Let's do a thought experiment. Say you have two walls facing each other on opposite sides of your room. You put a hook on each wall. You then take a piece of rope and tie the two hooks together. You exert some energy making the rope as taut as you possibly can. You crank it down and tie a strong knot in it. The rope now has tension; it is pulling the two walls together. The walls are strong, however, and don't move. The tension in the rope will be the same tomorrow or in the year 3000 as it is today, as will the forces on the walls. It certainly took energy to tighten the rope in the first place, but it doesn't require any energy to keep it taut.

If you assert that the rope requires energy to stay taut, where does this energy come from? Why does the rope use energy when it's taut, but not when it's just laying on the floor?

If the rope uses an exhaustible source of energy to stay taut, what happens when that energy source runs out? Does the rope somehow untie itself and fall off the hooks? Does it stay the same length but magically just stop pulling on the walls? Does it turn into soup and drip onto the ground?
This equation does not say what you think it says. You think it says that force requires a source of energy, presumably just because F appears on the left and E on the right. This is not sound reasoning. It's like saying that voltage requires a "source of current" because V = IR has voltage on the left and current on the right.

What you're doing is simply expressing a relationship between these quantities. Of course, E/c^2 is just the mass, so your equation is really just F=ma, or Newton's second law of motion. Forces and accelerations are related by mass. Mass and energy are related through c. Thus you can say that "force and energy are related through acceleration and c," but you're not saying anything new or novel. You're certainly not saying forces require sources of energy.
No, you don't. We've already explained to you that the human body is a complex machine, with individual muscle fibers contracting and then relaxing. You already wowed us with your high-school biology curriculum. We've already been over this. If your muscle fibers could contract and then simply stay locked in that position, you'd never get tired. They don't do that, though.
You can keep saying it, but it's still wrong.

- Warren

Nereid

And indeed they are (I don't think I said otherwise, did I?).

Since you did not answer my question, let me try to ask it in another way (perhaps you didn't understand my question):

PF is a forum for the discussion of physics, and other sciences. One of the cornerstones of science today is, in simple terms, the scientific method (please let me know if you are unfamiliar with what this is).

Since PF is about science, I personally expect that everyone who posts to the science threads in PF - and that includes Theory Development - has at least the intention of respecting the scientific method.

If a person has issues with the scientific method, then PF has a section where folk may discuss and debate that very topic.

When I read your posts, you appear (to me) to disparage the scientific method, and to consider it unworthy of your time to learn about it (which may explain why you don't appear to be interested to discuss the nature of science, in the Philosophy of Science and Mathematics section for example). A good example of what I mean is your apparent unwillingness to accept or consider scientific method-based questions and critiques of your own ideas.

To ask again: why are you here?

urtalkinstupid

That's what I'm trying to say.

That equation relates energy and mass to force. There are two types of forces: those that arise from mass and those that arise from energy. Energy forces are the kinds that work at a distance. I.E. Earth-Moon system, because that is a lot of force (energy) to keep moon in orbit. The space in between them is said to be the force of attraction. This has to be energy, there is no mass to constitute the force in between them. Ok, so it does not require an energy source, but an energy source would better explain how the attraction works. New or novel, nice job on being redundant. It takes energy to push or pull for anything. This energy is directed through a force. Mass is just a compact form of energy; I'm sure you all know that.

Ok, new analogy.

You weigh a certain amount of Newtons. Gravity pulls on you that exact force, thus cancelling it, right? You go up to a box. The box weighs 20N and, you push with 20N. The forces cancel out, thus making you unable to push the box. Now, you pull on the box with 30N. Not only are you moving the box, but you are also doing work. You are the only thing that is losing energy, not the box. How can the box not lose energy? You go and wrestle with a friend. You both pull each other with 20N of force; you two don't move. One pulls the other with 30N while the other with 20. You both get tired in this situation. It requires an energy for BOTH sources to keep on doing it. Yes, the human body is copmlicated, but the overall outcome is that your body takes a mass and converts it to energy to be used as the force applier. Everything needs some type of source, whether it be mass or energy, to apply a continous source. If they apply a continous force forever, this requires an unlimited source.

chroot, AP is college-level classes. So, get it right.

chroot

urtalkinstupid,

I asked you some specific questions. So did Nereid. Why are you not answering them?

And once again, this is nothing but abject speculation.
And thus falls this new theory of yours, just like the last one.

- Warren

Doc Al

So far, so good. Huh? The pull of gravity is your weight. Are you saying gravity cancels itself?
I assume you mean lift with 20N? It would require a slight bit of extra force to accelerate the box from rest. I assume you mean that you exert an upward force of 30N on the box. It will accelerate. And yes you are doing work on the box. You are converting chemical energy into heat and mechanical energy, some of which you are transfering to the box. Huh? The box gains energy. I hope you realize that you always exert the same force on each other (assuming an ideal rope): that's Newton's 3rd law.
Whether you accelerate or not depends on the net force on you. The rope pulling on you is just one force. The ground also exerts a force on you.

LOL... can't happen. The reason why it takes energy for you to exert a force is not because "forces require energy", but because exerting a force involves your muscles in continual movement, contracting and relaxing. You are a biological system, not an inanimate object. Nonsense.

I trust you're not taking AP physics!

urtalkinstupid

Sorry, I didn't see your questions chroot.

Ok, so [itex]F=ma[/tex], and we all know mass is related to energy. Mass is a compact form of energy, thus giving energy the greater quantity. It takes an emmence amount of energy to compose mass, it takes much more energy to make a suitable force between two objects. (or in this case three). Take away gravity and frictional forces, what are you left with? A loosely fit rope between two walls. It is no longer taut. No longer is energy acting through force on the objects. This energy arises between the forces that are applied. It's source?...I don't know. It's not my case to state that. That's simply my question that I'm asking you people. The rope uses energy when it is on the floor. It is held down by gravity, this is a force, and it is in the form of energy.

I stated above, "Take away gravity and frictional forces, what are you left with?" You take away forces, and the energy that keeps the rope taut is gone. It doesn't untie itself, it simply gets loose, allowing the walls to move in or accelerate in one directionas a system of the two walls and rope. Wall and rope soup...Sounds like the soup of the day.

No, but I implied that you took it into assumption that your opinion was right. Otherwise you wouldn't question my presence on this forum.

I'm here for the heck of it. I like this site, though I'm liked by very few...none. You people have actually inspired me to make a website based on the Standard odel. Isn't that exciting. A site made by me with no absurd theories! Perhaps, I will understand the Standard Model more?? Maybe, I'm here to play as the devil's advocate. Just to spur up debates. Who knows?

urtalkinstupid

Sorry, poorly worded. What I meant was gravity is what holds you down to the Earth's surface. Not what I said. Told you guys I'm bad at wording, heh.

No, I actually meant what I said, this time. Lift makes a better scenario though. Doc Al, you are cool unlike others.

I'm aware of that; I added that in there for clarity. As you noted in the progression of this scenario.

You said it yourself: It can. If one is more powerful than the other, one pulls with more force. Just like lifting a box. If you lift with more force than the box has, you overcome its force.

Heh, I'm taking AP Physics B.

Doc Al, at least you aren't mean like the others.

chroot

Then you're saying the rope uses energy in being acted upon gravitationally, and it also uses energy in being held taut. This means that the taut rope is actually using more energy than the rope on the ground, since the taut rope is having to expend energy both in having weight and in being taut. If the rope is using more energy, shouldn't it run out of that energy more quickly? If so, you have a clear experiment that can be done to test your theory.
The tension in the rope is maintained via intermolecular bonds. The atoms in the rope are bound together chemically. If this rope is to just suddenly run out of energy, give up and go limp, it must actually break chemical bonds to do so. This means that the rope, after giving up, will be fundamentally different from the original rope. Since it ran out of energy, you should now be able to do all sorts of paradoxical things with it. For example, tie that piece of rope between two tractors and have them pull against it. If the rope is no longer capable of supporting tension (it ran out of energy to do so) then it will simply stretch and stretch forever -- it can't exert any more forces, but it can't untie itself from the tractors either. It must just keep getting longer. This is the "rope soup" I was getting at.

Now, people have been using ropes and building materials for a very long time. The Earth itself has been around for almost 5 billion years, and its crust still seems to have the energy required to exert a force on me to keep me from falling through it. If this phenomenon (materials running out of energy to exert forces) really happens, why have we never seen it anywhere in the entire universe?
We do not welcome such people here.

- Warren

Nereid

There you go again, making unwarranted assumptions Thank you for your answer.

Do you consider PF to be a site where physics (and other sciences) is discussed, as science?

Do you recognise that discussion of physics, as a science, should be conducted on its own terms? In case this isn't clear, let me give you an analogy: if we are having a discussion on apple pie in the context of cooking, recipes and so forth, I personally would not consider it appropriate to talk about sexual fantasies concerning apple pies in that discussion, or whether the Sun is powered by a giant apple pie.

urtalkinstudid, just so that you don't make any further unwarranted assumptions, let me be clear as to my intention: I think the evidence is overwhelming that you are a troll, and so feel that you should be immediately banned from PF. However, I first want to make sure that you really do understand what PF is and what it's trying to do.

(for the avoidance of doubt, I personally have no power to ban anyone)

Doc Al

Two very different situations:
(1) Two guys yanking on a rope: the force they exert is always the same. Or: You and superman are arm-wrestling: I don't care how strong he is, whatever force he exerts on you will exactly equal the force that you exert on him. Note that these forces are on different objects, so they don't "cancel". This is Newton's 3rd law: learn it.

(2) Lifting a box. The acceleration of the box depends on the total force on the box. You lift with 30N, gravity pulls with 20N, so the box accelerates. This is Newton's 2nd law: learn it.

Then you'd better learn about Newton's laws before that class starts!
Give it time.

Alkatran

It doesn't take energy to make a force, we've already told you this. A force isn't energy either, unless it's over a distance. It's like using a charge to make a distance, makes no sense.

Same argument as above. Your posts are so full of BS it's scary.


Stop trying to argue by being clever (soup of the day), it won't work here and should only be done when you're actually making a valid point. I refer you to Chroot's post about the rope stretching forever.

If you have an opinion you MUST think it's right. That's what an opinion is.


I'm more for the ban every post.

beatrix kiddo

this is so ridiculous..
if anyone should be banned, its people who aren't questioning the current model. stupid is just pointing out what he thinks provides evidence for his case. just because u don't agree with it doesn't mean u have the right to ban him. this is TD and criticism is welcome, but to the point where someone gets banned, especially if they aren't saying anything vulgar, is crossing the line. are u afraid this is going to be another neutrino debate, soon? i was actually hoping for it, with the exclusion of another whack ultimatum...

beatrix kiddo

but mass is energy and it takes mass to make force...

well help to eliminate the bull-**** and answer the question...

duh.. but doesn't mean it is right...