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Thread: Energy and Force?

  1. #1 Energy and Force? 
    Forum Freshman LotusTiger's Avatar
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    I've you see in fact been trying to get a more detailed picture of energy and force. Well you'd say and could say I've got a number of explanations of it I've found from various members on the forum. In one of these explanations at the bottom potential energy isn't considered energy as nothing that is is "moving". It's as in fact only considered potential energy as under certain circumstance it would cause energy or movement. In here with the exp had of the force of the pressure against the dam what is the potential energy as a totality of things, dam, pressure, water. Where do we define this totality? This then intelligent member here said that there is no energy if no change in velocity happens. Is that true and if energy is "movement itself" is it right to say in fact that. In this the water may not change velocity but it's moving? A member who said something again as and as in fact as intelligently said energy is force by distance. However does this mean that the energy is all these things. What is the force, the distance the mass travels and the mass itself or is it better as rather to say energy is the mass travelling over a distance as a "result" of the force but the force is not defined as part of the definition of energy here as an arising example of energy. Also really is energy just movement "itself". However light enegry is "what" moves something not the "thing moved" such as crookes radometer. Is energy the thing moved or what moves it or both?

    In the Strong force as we do know there are quarks being held together in protons and neutrons while the residue of that would be the strong force that is holding together these hadrons the neutrons and protons together. A force is being exerted but I've read in fact for something to be a force it must change the rate of velocity of something. In the strong force in this example it isn't doing that. The particles aren't moving because of the strong force instead as it does appear that is their being pushed up against the wall as to speak. Their being glued as you could then say. No change in velocity is then happening. Well then is it that we should then take it that this is an example of an arsing of the strong force because it has what is the potential there to change velocities as can be seen by observation.



    A Comet going through space has potential energy because it's moving now, and it already has been accelerated in the past (to get it to its present speed), and it's possible it could be decelerated again back to a lower speed by colliding with something. So again: potential energy is energy.

    Now I feel bad, because I might have confused the OP by suggesting that potential energy wasn't energy. I guess it's more accurate to say that the motion of the comet doesn't expend energy (just stores it), and the string of a loaded crossbow also doesn't expend energy (just stores it). But the comet, and crossbow string are examples of energy



    That's actually the most accurate. Energy = Force x Distance

    If a force is applied, but nothing moves, then Distance = 0

    So: Energy = Force x Zero = 0

    Energy is force times displacement:


    Energy is only considered to take place if something moves (and even then, it has to be changing speed, not just coasting at a fixed speed), so the force of gravity isn't considered energy (it's considered potential energy). Or consider a hydro-electric dam, that isn't allowing any water through it for the moment. The force of the pressure of the water against the dam isn't energy. (It is potential energy, however). It's only when the water actually passes through the dam that you get energy.


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  3. #2  
    Forum Freshman gottaBtold's Avatar
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    Interesting post, Lotus Tiger. I am not a mathematician, nor a scientist, but have a keen interest in exploring the fields. In thinking about some of what you've said here, a couple of things came to mind and I wonder if some of the difficulty might be in semantics - is it "force", or is it "energy"?

    One - the Conservation Laws (momentum, energy, angular momentum) might be worth further consideration.

    Two - Einstein covered "at rest" and "relativistic" conditions. These should work in describing energy for your water-behind-a-dam, the cross-bow, or comet, don't you think?


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  4. #3  
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    I disagree with whoever said that potential energy is not energy. It is a form of energy. The form of energy that involves moving objects is called kinetic energy. Potential energy can be converted to kinetic energy or vice versa.

    If the water behind the dam is released it goes down the hill, losing potential energy and gaining kinetic energy. If it strikes something at the bottom of the hill it can transfer some of this kinetic energy to another object by applying a force over a distance. The force multiplied by the distance is called "work" and is another measure of energy.

    There is no reason to apply Einsteins theory of relativity in this situation. Classical mechanics will do nicely.
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  5. #4  
    Forum Freshman LotusTiger's Avatar
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    A confusion between Energy and Force?

    I'd say that is in terms with work the work that is done is equal to the force multiplied by the displacement. Well in fact that's what's said. Energy also is the ability to do work.The amount of energy something has is the amount of work it can do. The joule is the unit of energy and work but this actually is extremely confusing well that's how I see it.

    If energy is the amount of work something can do this well then is saying the amount of energy is synonymous with the amount of force in fact multiplied by the displacement as that's work. This well makes it sound that if energy is what is the ability to do work force then is a form of energy as it causes a displacement, movement and velocity. How can work be equal to the "force" multiplied by the displacement and then say "energy" does work ( that is in other words leads to a displacement and then even with how work is more accurately defined a "force" multiplied by a displacement" In fact that energy does that ,as that's what's being said as it does work) Wasn't it I then thought that force that is what does well what is work. Is force then, energy? As we do say yes energy does "work" as energy is the amount of work something is capable to do? I'd thought the unit for energy and force are different, here they seem the same.

    What is, force or energy can then move or give something a velocity. Then is velocity something that either can come from force or energy. We say energy is measured in J joules and force in N Newtons. Do we say there is a notional symbol that can either stand for force or energy?
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  6. #5  
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    No, force isn't energy. They have different units. Force is in newtons and energy is in newton-meters.
    Look, you are not going to talk your way into understanding it. Get a hold of a physics book and work some example problems. Then it will begin to dawn on you what we are talking about.
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  7. #6  
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    I was under the impression that the definition of "energy" was still not clearly defined. Perhaps this is the cause of the confusion?
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  8. #7  
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    Quote Originally Posted by Harold14370 View Post
    No, force isn't energy. They have different units. Force is in newtons and energy is in newton-meters.
    Look, you are not going to talk your way into understanding it. Get a hold of a physics book and work some example problems. Then it will begin to dawn on you what we are talking about.
    Excellent advice.

    The Feynman Lectures on Physics is a good physics text.
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  9. #8  
    Time Lord
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    Energy vs. Force is kind of a Tortoise vs. Hare type of question. The hare could run really fast over a short period of time before getting tired and needing to rest. The tortoise had endurance to keep running (though not very fast) until the end. Energy is the tortoise situation of not only exerting a lot of force, but being able to keep exerting it for a while.

    It's more clear in chemical interactions. For example, nanothermite puts out the same energy as ordinary thermite. However, because the nanothermite is separated into tinier granules, the reaction happens more rapidly leading to higher temperatures. However, those temperatures are sustained over a much shorter time.
    Some clocks are only right twice a day, but they are still right when they are right.
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