What is energy's role in natural forces like gravity and magnetism?

[Momento]

Hallo,

When force is acted upon a certain object it could change its direction,movement. Does force require energy to be produced?

Looking at all the natural forces they seem to be created and force comes along with them. If force can move an object or stop an object or ever accelerate one. What is energy's role in all of them? Is it like this example:

Magnetic fields producing a natural force that can only be triggered by energy, same as gravity. Are natural force only triggered by energy?

 

[Drakkith]

Hallo,

When force is acted upon a certain object it could change its direction,movement. Does force require energy to be produced?

The short answer is no, but it is kind of a complicated question.

Looking at all the natural forces they seem to be created and force comes along with them. If force can move an object or stop an object or ever accelerate one. What is energy's role in all of them? Is it like this example:

Magnetic fields producing a natural force that can only be triggered by energy, same as gravity. Are natural force only triggered by energy?

I think you have a misunderstanding of what energy is. Energy is simply the ability for one system to perform work on another. Energy does not cause things to happen, that is the result of forces.

 

[haruspex]

When force is acted upon a certain object it could change its direction,movement. Does force require energy to be produced?

The key word is could. If it does not in fact change anything, no work has been done. Work = force * distance through which the force produced movement of the point of application, in the direction of the force.

 

[Momento]

The short answer is no, but it is kind of a complicated question.



I think you have a misunderstanding of what energy is. Energy is simply the ability for one system to perform work on another. Energy does not cause things to happen, that is the result of forces.

If force is produced over a distance is there energy being stored/converted...?

The key word is could. If it does not in fact change anything, no work has been done. Work = force * distance through which the force produced movement of the point of application, in the direction of the force.

So force is crucial for a system to do work right?

 

[sophiecentaur]

If force is produced over a distance is there energy being stored/converted...?



So force is crucial for a system to do work right?

In as far as it's included in the definition, you can't have one without the other.
If the car's not in gear (to transmit a force), the engine can't do any work in getting it moving.

 

[haruspex]

So force is crucial for a system to do work right?

That doesn't logically follow. I stated how a force does work. Perhaps things other than forces can do work. Heat flow, e.g.

 

[sophiecentaur]

Nope. 'Work' is a strictly defined quantity, involving force and displacement. You are trying to associate work with energy in general, which is not precise.

 

[haruspex]

Nope. 'Work' is a strictly defined quantity, involving force and displacement. You are trying to associate work with energy in general, which is not precise.

That's not universal. Many authorities distinguish between mechanical work, electrical work, chemical work and thermodynamic work (heat).

 

[sophiecentaur]

That's not how I am used to it. Do you have a reference to these other uses of the word? There seems little point in expanding its meaning so that it becomes synonymous with 'Energy' or 'Potential'.
I do know that 'work function' is used in respect of the energy required to remove photo-electrons but even that involves a mechanical idea, albeit small scale. (And it is a fairly ancient concept along with Electro Motive Force)

 

[DrewD]

I am far from an authority, but I have never heard heat referred to as thermodynamic work. In fact, the two are strictly different according to the first law of thermodynamics. Electrical work is the work done on a charged particle by the electric field. A charged particle feels a force in an electric field.
These specific cases of work can be distinguished, but the definition of work requires a force. If you don't explicitly define a force, it follows from the definition that $-\frac{dW}{dr}=F$.
I would be surprised to see work used in a situation where a force could not be easily defined unless the author was explicitly being loose with definitions.

 

[haruspex]

That's not how I am used to it. Do you have a reference to these other uses of the word? There seems little point in expanding its meaning so that it becomes synonymous with 'Energy' or 'Potential'.
I do know that 'work function' is used in respect of the energy required to remove photo-electrons but even that involves a mechanical idea, albeit small scale. (And it is a fairly ancient concept along with Electro Motive Force)

It's not so much a matter of expanding the meaning. It's more that the meaning of the word "work" has tended to contract to cover only mechanical work in most usage. It's a bit like the use of "forensic" to mean specifically forensic science. It really means "pertaining to law".
Early statements of the laws of thermodynamics included "heat is work and work is heat". The term energy was not so widespread.
But I was wrong to say thermodynamic work meant heat - it's everything except heat. For the rest, see http://en.wikipedia.org/wiki/Work_(thermodynamics).

 

[Momento]

Ok, Some of you are realting work to energy and I doubt their the same. I'm kinda confused and stuck in the middle here...

All I know now is a system that is able to work will always require "Force" to do so. In many system their are countless forces that have to come into account. Some forces are already being generated from a system's energy and other may have forces upon them such as you and I and all objects that have gravitational force on them.

"sophiecentaur" has a good point about the matter so far.

 

[Momento]

It's not so much a matter of expanding the meaning. It's more that the meaning of the word "work" has tended to contract to cover only mechanical work in most usage. It's a bit like the use of "forensic" to mean specifically forensic science. It really means "pertaining to law".
Early statements of the laws of thermodynamics included "heat is work and work is heat". The term energy was not so widespread.
But I was wrong to say thermodynamic work meant heat - it's everything except heat. For the rest, see http://en.wikipedia.org/wiki/Work_(thermodynamics).

But isn't heat energy from its origins? I mean heat is the act of atoms having a lot of movement isn't it, so that's energy right?

 

[DrStupid]

But isn't heat energy from its origins?

Heat and work are exchange of energy.

 

[haruspex]

All I know now is a system that is able to work will always require "Force" to do so.

If you only consider work to cover mechanical work then, yes, force will be required.
The references I've found show that 'work' nowadays means any form of energy other than heat, and that if you care about the specific form of work then you should qualify it as mechanical, chemical, electrical, and so on.
For some of these it is not so clear that there would always be a force involved in transfer. Is there a force involved when a photon excites an electron in an atom? Maybe.

 

[Drakkith]

For some of these it is not so clear that there would always be a force involved in transfer. Is there a force involved when a photon excites an electron in an atom? Maybe.

The interaction by which any transfer of energy takes place is the result of a force. Without a force there would be no interaction between two particles and no energy would be exchanged.

 

[Dead Boss]

The interaction by which any transfer of energy takes place is the result of a force. Without a force there would be no interaction between two particles and no energy would be exchanged.

I would say force is a result of interaction not the other way around.

 

[Momento]

The interaction by which any transfer of energy takes place is the result of a force. Without a force there would be no interaction between two particles and no energy would be exchanged.

Thank you! Thats what I've been looking for. Force is crucial in a system to convert energy from its orignal form to another. Thats why we mainly use the formula W = F x D...

I just need to know that force is the tool for energy to use to be able to do "work". Without it you would not be able to do anything with that energy. Hope I'm on the right page here.

 

[Momento]

I would say force is a result of interaction not the other way around.

Honestly doubt that.

 

[CWatters]

I just need to know that force is the tool for energy to use to be able to do "work". Without it you would not be able to do anything with that energy. Hope I'm on the right page here.

I think that even applies to electrical or chemical systems.

 

[Momento]

I think that even applies to electrical or chemical systems.

I think it would apply to all those system. However, heat is another different matter...

 

[sophiecentaur]

It's not so much a matter of expanding the meaning. It's more that the meaning of the word "work" has tended to contract to cover only mechanical work in most usage. It's a bit like the use of "forensic" to mean specifically forensic science. It really means "pertaining to law".
Early statements of the laws of thermodynamics included "heat is work and work is heat". The term energy was not so widespread.
But I was wrong to say thermodynamic work meant heat - it's everything except heat. For the rest, see http://en.wikipedia.org/wiki/Work_(thermodynamics).

Flanders and Swann did a memorable rendition of this, way back.

 

[Drakkith]

Thank you! Thats what I've been looking for. Force is crucial in a system to convert energy from its orignal form to another. Thats why we mainly use the formula W = F x D...

I just need to know that force is the tool for energy to use to be able to do "work". Without it you would not be able to do anything with that energy. Hope I'm on the right page here.

Well, I would say that energy doesn't do work at all. Forces do work and a change is incurred in the system. Energy is simply a measure of how much work something can do.

 

[Nano-Passion]

Well, I would say that energy doesn't do work at all. Forces do work and a change is incurred in the system. Energy is simply a measure of how much work something can do.

I think it is a pointless distinction. Let us forget about force fields so we can separate force and energy from each other. Now if I throw a ball in space, we have something called kinetic energy and that energy can do work on object B when it is in contact.

But you could just as easily say that it is the force that did work by the equation F=ma. I accelerated mass A and it hits object B with force F and does work.

So which one is the "culprit"?

 

[Drakkith]

The work done is going to depend on all the properties of an object, from it's mass to it's velocity to whichever forces it interacts by. (Along with the same things for the object it interacts with)

But if one were to choose which one does the work I would say it is the force. If two particles don't interact by a force at all, then they cannot perform work on each other. But then would the particles still have energy, at least with respect to one another? I don't know.

 

[Momento]

The work done is going to depend on all the properties of an object, from it's mass to it's velocity to whichever forces it interacts by. (Along with the same things for the object it interacts with)

But if one were to choose which one does the work I would say it is the force. If two particles don't interact by a force at all, then they cannot perform work on each other. But then would the particles still have energy, at least with respect to one another? I don't know.

I really like you descriptions! I believe that FORCE is the key for work without as I said before work can't be done. Really really interesting thing. Thank you so much for you're answers!

For all the others I appreciate you're effort too! Thing is we could all agree at a certain point that without force the system can NOT do any work at all! I'd be glade to read more ideas from anyone else!

 

[Momento]

If force was applied to an object will there be work done? Would there be energy stored?

I think that force is the main reason why energy could possibly be converted... Like friction its a force on moving objects it converts their energy into heat, its possible that it could convert it to another form of energy?

 

[Nano-Passion]

The work done is going to depend on all the properties of an object, from it's mass to it's velocity to whichever forces it interacts by. (Along with the same things for the object it interacts with)

But if one were to choose which one does the work I would say it is the force. If two particles don't interact by a force at all, then they cannot perform work on each other. But then would the particles still have energy, at least with respect to one another? I don't know.

True, for kinetic energy to happen there needs to be a force (acceleration or "imbalance" if you will).

 

[Nano-Passion]

If force was applied to an object will there be work done?

Yes work is done when ever you displace an object X distance. Force does work because it accelerates things, and hence displaces it.

Would there be energy stored?

Well it kind of depends on what you mean by stored. Under certain parameters like in gravitational fields where energy is conservative, potential energy is stored.

Based on other principles, you can argue that kinetic energy is given to the object since it picks up velocity. Whether you want to call that stored is semantics.

I think that force is the main reason why energy could possibly be converted... Like friction its a force on moving objects it converts their energy into heat, its possible that it could convert it to another form of energy?

I'm not following this point.

 

[Momento]

I'm not following this point.

Look at the rotational kinetic energy of a wheel that is being rotated by a motor for example.
That motor would convert electricity into mechanical energy to rotate the wheel. Let's say based on the work model 1000J was supplied of electricity, if the motor would lose some of that energy due to countless reason. One of them is "Friction" of the bearings.

Now friction is a force, it distribute a small amount of the 1000J to another form of energy like heat,sound,etc...

 

[grantwilliams]

If force was applied to an object will there be work done?

Isn't that only true if force is in the same direction as motion?

 

[Drakkith]

Isn't that only true if force is in the same direction as motion?

No, if you apply a force against an object to slow it down you have done work.

 

[grantwilliams]

No, if you apply a force against an object to slow it down you have done work.

And I guess a torque applied causes work to be done if the object has a radial displacement.. my bad.

 

[Momento]

No, if you apply a force against an object to slow it down you have done work.

Makes sense. A force was applied over a distance to stop a moving object which represents this model: W = F x D?

Thats way work is done?

 

[Momento]

Is it safe to say that "Energy" is the measurement of work done in a system? And that Force is crucial for Work to be converted?