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what is the relation between force and energy?

what is the relation between force and energy? - Physics Forum

what is the relation between force and energy? - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


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  #1  
Old 09-20-2004, 09:11 AM
yogesh
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Default what is the relation between force and energy?



Both stress and pressure can be defined as energy/volume.
i.e they have the potential to do some amount of work per unit volume.

Now based on the similar lines, can *force* be called as
*energy/length*.?

If I know the *force* how can I conclude about the *work* it will
going to produce or *energy* i.e its potential.
In other words, what is the relation between *force* and *energy*?

If I only know the forces acting on the systems,can I come to know
about the energy content in that system.?

Thank you..
regds,
Yogesh Joshi
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  #2  
Old 09-20-2004, 10:45 AM
Bjoern Feuerbacher
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Default what is the relation between force and energy?

yogesh wrote:

That would be a strange way to define them. The standard definition
is still force/area.




work/length would be more appropriate.



Look up the definition of work.

The simple-minded one:
work = force times distance during which the force is acting

Not-so-simple minded:
work = force times distance during which the force is acting,
in the direction of the force

Real one:
work = integral of the force along the path on which it is acting




You can't.


Bye,
Bjoern
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  #3  
Old 09-20-2004, 01:39 PM
N:dlzc D:aol T:com \(dlzc\)
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Default what is the relation between force and energy?

Dear yogesh:

"yogesh" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ] m...
....

No, because you don't know the *history* of those forces, and you don't
know what initial energy the systems had wrt you.

David A. Smith


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  #4  
Old 09-20-2004, 02:17 PM
puppet_sock@hotmail.com
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Default what is the relation between force and energy?

[Only registered users see links. ] (yogesh) wrote in message news:<f88a27e4.0409200111.bd7020a@posting.google.c om>...

Note, though, that just becaust they have those units does not make
stess and pressure the same thing. In general, stress is a tensor,
and the usual formulation of pressure is as a scalar.

You need to get yourself a good senior highschool or first year
university textbook and study up.


And force is a vector. So you might, in some situations, think
of its units that way. But it's misleading to think of force
*as* work/length. That is only the units.


Work is force dotted into the displacement it acts through.

W = F.d

where F and d are both vector quantities.


Maybe, but not in general.

In some cases, the forces may be enough to work out the motions
involved. But in the general case you will need more. And to
calculate the work done you need the displacement that each force
is applied through. And it is not the case that you can work
this out with only the forces in at least some cases. You would
need some other boundary conditions in general, such as starting
velocities, masses, and maybe other stuff as well.
Socks
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  #5  
Old 09-20-2004, 04:35 PM
yogesh
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Default what is the relation between force and energy?

> > If I only know the forces acting on the systems,can I come to know
But if I know the pressure ( or if I can calculate the pressure from
the forces) then certainly I know the energy/volume of the system.


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  #6  
Old 09-20-2004, 04:56 PM
rsm109@york.ac.uk
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Default what is the relation between force and energy?

[Only registered users see links. ] (yogesh) wrote in message news:<f88a27e4.0409200111.bd7020a@posting.google.c om>...

The work done is the integral of the force along the path taken. The
change in potential energy is the negative of this. Conversely, the
force acting on a particle at a point is the negative of the gradient
of the potential at that point.
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  #7  
Old 09-20-2004, 04:56 PM
Bjoern Feuerbacher
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Default what is the relation between force and energy?

yogesh wrote:

No. Why do you think so? Pressure has the same units as energy/volume.
But pressure is not the same as energy density!


Bye,
Bjoern
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  #8  
Old 09-20-2004, 05:08 PM
robert j. kolker
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Default what is the relation between force and energy?



yogesh wrote:


Since the work took an interval of time to do, the best you can say is
average energy/unit of time.

Bob Kolker


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  #9  
Old 09-20-2004, 05:14 PM
TomGee
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Default what is the relation between force and energy?

[Only registered users see links. ] (yogesh) wrote in message news:<f88a27e4.0409200111.bd7020a@posting.google.c om>...
Einstein's E=mc^2 formula stipulates what energy is equal to, but it
does not say what energy is. Energy is defined in one way as "a
vigorous exertion of power," and power is defined as having the
"...ability to act or produce...(or undergo)...an effect." Force, a
synonym for power, "...implies the actual effective exercise of
power." Energy, as heat, produces light, which is, in effect, "a
vigorous exertion of power." Such exercise of power is a force;
therefore, energy is a force.
TomGee
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  #10  
Old 09-21-2004, 02:51 AM
Old Man
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Default what is the relation between force and energy?


"Bjoern Feuerbacher" <[Only registered users see links. ]-heidelberg.de> wrote in message
news:cin23v$946$[Only registered users see links. ].uni-heidelberg.de...

Old Man has the thought that, in GTR, the energy
density from pressure gravitates.

The "water potential" (J / m^3) inside a cellular membrane
can be measured as a pressure difference (Pascals). One
can also measure the vapor pressure of the cellular fluid.
This is equivalent to measuring thedecreasrd (negative)
cellular water potential due to the presence of solutes, called,
"osmotic potential". In plant cells, the water potential is
the algebraic sum of positive cell pressure (turgor) and the
negative osmotic potential of the cell water.

[Old Man]


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