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More options Apr 13 2012, 7:29 am
Newsgroups: sci.electronics.design, sci.physics
From: HardySpicer <gyansor...@gmail.com>
Date: Fri, 13 Apr 2012 04:29:21 -0700 (PDT)
Local: Fri, Apr 13 2012 7:29 am
Subject: Energy in a permanent magnet question
Suppose I have a permanent magnet and attract a nail a height h from
the ground. If the nail has mass m then I have done mgh of work
(potential energy)  which must come from the field. If I then attract
a second nail the magnetic attraction will be less since I have used
energy when attracting the first one - which is still attached. If I
keep doing this there is little energy left to lift anything more.

I then pull off the nails which requires energy from me. That energy
must be released back into the field since I can then replicate the
experiment. Is this right? So energy is stored in permanent magnets.

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More options Apr 13 2012, 7:35 am
Newsgroups: sci.electronics.design, sci.physics
From: brent <buleg...@columbus.rr.com>
Date: Fri, 13 Apr 2012 04:35:36 -0700 (PDT)
Local: Fri, Apr 13 2012 7:35 am
Subject: Re: Energy in a permanent magnet question
On Apr 13, 7:29 am, HardySpicer <gyansor...@gmail.com> wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy)  which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

> I then pull off the nails which requires energy from me. That energy
> must be released back into the field since I can then replicate the
> experiment. Is this right? So energy is stored in permanent magnets.

For a mere \$31 you can find the answer to your question here:

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More options Apr 13 2012, 9:35 am
Newsgroups: sci.electronics.design, sci.physics
From: George Herold <gher...@teachspin.com>
Date: Fri, 13 Apr 2012 06:35:25 -0700 (PDT)
Local: Fri, Apr 13 2012 9:35 am
Subject: Re: Energy in a permanent magnet question
On Apr 13, 7:29 am, HardySpicer <gyansor...@gmail.com> wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy)  which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

> I then pull off the nails which requires energy from me. That energy
> must be released back into the field since I can then replicate the
> experiment. Is this right? So energy is stored in permanent magnets.

Here's how I would think about it.

There is energy in the magnetic field.  The energy density is B^2/
(2*mu sub zero) (MKS units) If you integrate this over all space you
get the total energy in the field.  Sticking bits of iron in the field
reduces the B field outside the pieces of iron and so the total energy
of the system has decreased.
So sure there is some energy in any magnet.  (I trust this is *not*
leading to some perpetual motion gizmo.)

George H.

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More options Apr 13 2012, 9:44 am
Newsgroups: sci.electronics.design, sci.physics
From: n...@puntnl.niks (Nico Coesel)
Date: Fri, 13 Apr 2012 13:44:21 GMT
Local: Fri, Apr 13 2012 9:44 am
Subject: Re: Energy in a permanent magnet question

HardySpicer <gyansor...@gmail.com> wrote:
>Suppose I have a permanent magnet and attract a nail a height h from
>the ground. If the nail has mass m then I have done mgh of work
>(potential energy)  which must come from the field. If I then attract
>a second nail the magnetic attraction will be less since I have used
>energy when attracting the first one - which is still attached. If I

Magnets don't have anything to do with energy. They exert a force. The
energy comes from whatever is moving/holding the magnet or the object.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

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More options Apr 13 2012, 9:45 am
Newsgroups: sci.electronics.design, sci.physics
From: Helmut Wabnig <hwabnig@.- --- -.dotat>
Date: Fri, 13 Apr 2012 15:45:34 +0200
Local: Fri, Apr 13 2012 9:45 am
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 04:29:21 -0700 (PDT), HardySpicer

<gyansor...@gmail.com> wrote:
>Suppose I have a permanent magnet and attract a nail a height h from
>the ground. If the nail has mass m then I have done mgh of work
>(potential energy)  which must come from the field. If I then attract
>a second nail the magnetic attraction will be less since I have used
>energy when attracting the first one - which is still attached. If I
>keep doing this there is little energy left to lift anything more.

>I then pull off the nails which requires energy from me. That energy
>must be released back into the field since I can then replicate the
>experiment. Is this right? So energy is stored in permanent magnets.

No, it's not right.

But you don't want to know anyway.

The energy stored in a magnet is called magnetization work.
If you extract it, you will de-magnetize the magnet.

Coercitivity
Susceptibility
Remanence
Degaussing

w.

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More options Apr 13 2012, 10:12 am
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com>
Date: Fri, 13 Apr 2012 07:12:41 -0700
Local: Fri, Apr 13 2012 10:12 am
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 13:44:21 GMT, n...@puntnl.niks (Nico Coesel)
wrote:

>HardySpicer <gyansor...@gmail.com> wrote:

>>Suppose I have a permanent magnet and attract a nail a height h from
>>the ground. If the nail has mass m then I have done mgh of work
>>(potential energy)  which must come from the field. If I then attract
>>a second nail the magnetic attraction will be less since I have used
>>energy when attracting the first one - which is still attached. If I

>Magnets don't have anything to do with energy.

They certainly store energy. It takes energy to magnetize one, and the
nail experiment is one way to recover some of that energy.

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

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More options Apr 13 2012, 10:33 am
Newsgroups: sci.electronics.design, sci.physics
From: Helmut Wabnig <hwabnig@.- --- -.dotat>
Date: Fri, 13 Apr 2012 16:33:33 +0200
Local: Fri, Apr 13 2012 10:33 am
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 07:12:41 -0700, John Larkin

No, Mista.

If you pull out energy (regardless how),
the magnet would de-magnetize.

w.

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More options Apr 13 2012, 10:47 am
Newsgroups: sci.electronics.design, sci.physics
From: Sam Wormley <sworml...@gmail.com>
Date: Fri, 13 Apr 2012 09:47:06 -0500
Local: Fri, Apr 13 2012 10:47 am
Subject: Re: Energy in a permanent magnet question
On 4/13/12 6:29 AM, HardySpicer wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy)  which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

No.

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More options Apr 13 2012, 10:56 am
Newsgroups: sci.electronics.design, sci.physics
From: halong <cco...@netscape.net>
Date: Fri, 13 Apr 2012 07:56:48 -0700 (PDT)
Local: Fri, Apr 13 2012 10:56 am
Subject: Re: Energy in a permanent magnet question
On Apr 13, 6:29 am, HardySpicer <gyansor...@gmail.com> wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy)  which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

> I then pull off the nails which requires energy from me. That energy
> must be released back into the field since I can then replicate the
> experiment. Is this right? So energy is stored in permanent magnets.

Not really,

It took you an amount of energy to set up this scenario :

> Suppose I have a permanent magnet and attract a nail a height h from

...When the nail jumps to the magnet, it's just paying you back what
you've spent out

So, tell this experiment to Obama and explain to him that the "no free
lunch in America" still works, and it's now biting him

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More options Apr 13 2012, 11:26 am
Newsgroups: sci.electronics.design, sci.physics
From: "tm" <No_one_h...@white-house.gov>
Date: Fri, 13 Apr 2012 11:26:22 -0400
Local: Fri, Apr 13 2012 11:26 am
Subject: Re: Energy in a permanent magnet question

"halong" <cco...@netscape.net> wrote in message

On Apr 13, 6:29 am, HardySpicer <gyansor...@gmail.com> wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy) which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

> I then pull off the nails which requires energy from me. That energy
> must be released back into the field since I can then replicate the
> experiment. Is this right? So energy is stored in permanent magnets.

Not really,

It took you an amount of energy to set up this scenario :

> Suppose I have a permanent magnet and attract a nail a height h from

...When the nail jumps to the magnet, it's just paying you back what
you've spent out

So, tell this experiment to Obama and explain to him that the "no free
lunch in America" still works, and it's now biting him

_________________________________________________

Or better yet see if you can get some of that green energy funding from the
dept of energy. Let us know if it works.

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More options Apr 13 2012, 11:34 am
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com>
Date: Fri, 13 Apr 2012 08:34:39 -0700
Local: Fri, Apr 13 2012 11:34 am
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 16:33:33 +0200, Helmut Wabnig <hwabnig@.- ---

So, when the magnet lifts a nail, where did the energy come from? Do
you believe in conservation of energy?

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

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More options Apr 13 2012, 11:53 am
Newsgroups: sci.electronics.design, sci.physics
From: Tim Wescott <t...@seemywebsite.com>
Date: Fri, 13 Apr 2012 10:53:05 -0500
Local: Fri, Apr 13 2012 11:53 am
Subject: Re: Energy in a permanent magnet question

It does demagnetize -- the more nails you put on, the less magnetic field
there is available to the outside world.  Then, when you pull the nails
off, you re-magnetize it.

And no, I don't mean "demagnetize" in the way that you were thinking --
and no, that's not my problem.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

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More options Apr 13 2012, 11:59 am
Newsgroups: sci.electronics.design, sci.physics
From: n...@puntnl.niks (Nico Coesel)
Date: Fri, 13 Apr 2012 15:59:31 GMT
Local: Fri, Apr 13 2012 11:59 am
Subject: Re: Energy in a permanent magnet question

If that where true a motor with permanent magnets would stop working
very quickly.

A magnet exerts a force. A magnet can attract things but it takes the
same amount of energy to remove those things so the nett output is 0.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

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More options Apr 13 2012, 12:22 pm
Newsgroups: sci.electronics.design, sci.physics
From: "Androcles" <H...@Hgwrts.phscs.Apr.2012>
Date: Fri, 13 Apr 2012 17:22:46 +0100
Local: Fri, Apr 13 2012 12:22 pm
Subject: Re: Energy in a permanent magnet question

"Tim Wescott" <t...@seemywebsite.com> wrote in message

news:ndidnfhNnZF81hXSnZ2dnUVZ_hudnZ2d@web-ster.com...

Because you are kook who doesn't know what a friend is.

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More options Apr 13 2012, 12:31 pm
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com>
Date: Fri, 13 Apr 2012 09:31:18 -0700
Local: Fri, Apr 13 2012 12:31 pm
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 10:53:05 -0500, Tim Wescott <t...@seemywebsite.com>
wrote:

Right. The captured nails shunt the field locally, leaving less
external field to lift future nails.

A thin coating of infinite-mu stuff would soak up all available
external-to-magnet energy, and shield the magnet perfectly.

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

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More options Apr 13 2012, 1:35 pm
Newsgroups: sci.electronics.design, sci.physics
From: Fred Bartoli <" ">
Date: Fri, 13 Apr 2012 19:35:39 +0200
Local: Fri, Apr 13 2012 1:35 pm
Subject: Re: Energy in a permanent magnet question
brent a écrit :

> On Apr 13, 7:29 am, HardySpicer <gyansor...@gmail.com> wrote:
>> Suppose I have a permanent magnet and attract a nail a height h from
>> the ground. If the nail has mass m then I have done mgh of work
>> (potential energy)  which must come from the field. If I then attract
>> a second nail the magnetic attraction will be less since I have used
>> energy when attracting the first one - which is still attached. If I
>> keep doing this there is little energy left to lift anything more.

>> I then pull off the nails which requires energy from me. That energy
>> must be released back into the field since I can then replicate the
>> experiment. Is this right? So energy is stored in permanent magnets.

> For a mere \$31 you can find the answer to your question here:

<http://web.archive.org/web/20060821171406/http://www.cip.csiro.au/Mac...>

Also see:
http://www.femm.info/wiki/PMEnergy

--
Thanks,
Fred.

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More options Apr 13 2012, 2:37 pm
Newsgroups: sci.electronics.design, sci.physics
From: spamtrap1888 <spamtrap1...@gmail.com>
Date: Fri, 13 Apr 2012 11:37:46 -0700 (PDT)
Local: Fri, Apr 13 2012 2:37 pm
Subject: Re: Energy in a permanent magnet question
On Apr 13, 7:12 am, John Larkin

I know from practical experience it takes energy to demagnetize them
as well -- perhaps as much or more to randomize the domains as it took
to align them.

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More options Apr 13 2012, 2:53 pm
Newsgroups: sci.electronics.design, sci.physics
From: CWatters <colin.watt...@NOturnersoakSPAM.plus.com>
Date: Fri, 13 Apr 2012 19:53:45 +0100
Local: Fri, Apr 13 2012 2:53 pm
Subject: Re: Energy in a permanent magnet question
On 13/04/2012 12:29, HardySpicer wrote:

> Suppose I have a permanent magnet and attract a nail a height h from
> the ground. If the nail has mass m then I have done mgh of work
> (potential energy)  which must come from the field. If I then attract
> a second nail the magnetic attraction will be less since I have used
> energy when attracting the first one - which is still attached. If I
> keep doing this there is little energy left to lift anything more.

> I then pull off the nails which requires energy from me. That energy
> must be released back into the field since I can then replicate the
> experiment. Is this right? So energy is stored in permanent magnets.

When an apple falls does the earth use up some of it's gravity?

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More options Apr 13 2012, 2:57 pm
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jlar...@highlandtechnology.com>
Date: Fri, 13 Apr 2012 11:57:02 -0700
Local: Fri, Apr 13 2012 2:57 pm
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 15:59:31 GMT, n...@puntnl.niks (Nico Coesel)
wrote:

That statement makes no sense. A motor gets its power from an external
power source, not from the energy stored in the magnet.

There's energy stored in the lockwashers too, but it doesn't get used
up.

>A magnet exerts a force. A magnet can attract things but it takes the
>same amount of energy to remove those things so the nett output is 0.

So I guess you would argue that a spring exerts force but never stores
energy. Then it follows that it takes no energy to compress a spring.

--

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

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More options Apr 13 2012, 3:04 pm
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jlar...@highlandtechnology.com>
Date: Fri, 13 Apr 2012 12:04:49 -0700
Local: Fri, Apr 13 2012 3:04 pm
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 11:37:46 -0700 (PDT), spamtrap1888

From a pure COE perspective, one should extract energy from a magnet
to demagnetize it. Lifting nails actually does that, some.

Hmmm, suppose you dissolve a magnet in acid. Where does the
magnetization energy go? It must come out as heat... there's (almost!)
nowhere else for it to go. That would make an interesting science
project experiment.

Similarly, if you heated charged and uncharged magnets to the curie
temperature, the charged magnet would require less heat. Maybe.

We need a good physical chemist to comment here.

--

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

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More options Apr 13 2012, 3:08 pm
Newsgroups: sci.electronics.design, sci.physics
From: John Larkin <jlar...@highlandtechnology.com>
Date: Fri, 13 Apr 2012 12:08:53 -0700
Local: Fri, Apr 13 2012 3:08 pm
Subject: Re: Energy in a permanent magnet question
On Fri, 13 Apr 2012 09:47:06 -0500, Sam Wormley <sworml...@gmail.com>
wrote:

>On 4/13/12 6:29 AM, HardySpicer wrote:
>> Suppose I have a permanent magnet and attract a nail a height h from
>> the ground. If the nail has mass m then I have done mgh of work
>> (potential energy)  which must come from the field. If I then attract
>> a second nail the magnetic attraction will be less since I have used
>> energy when attracting the first one - which is still attached. If I
>> keep doing this there is little energy left to lift anything more.

>   No.

Yes. Each nail stuck to the magnet shunts some of the field, reducing
external field, so there's less energy available to lift future nails.

A magnet can't yank up an infinite mass of nails.

--

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

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More options Apr 13 2012, 3:27 pm
Newsgroups: sci.electronics.design, sci.physics
From: m II <C...@in.the.hat>
Date: Fri, 13 Apr 2012 13:27:34 -0600
Local: Fri, Apr 13 2012 3:27 pm
Subject: Re: Energy in a permanent magnet question
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Hash: SHA1

Energy is neither created or desproinged?

mike

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More options Apr 13 2012, 3:34 pm
Newsgroups: sci.electronics.design, sci.physics
From: n...@puntnl.niks (Nico Coesel)
Date: Fri, 13 Apr 2012 19:34:33 GMT
Local: Fri, Apr 13 2012 3:34 pm
Subject: Re: Energy in a permanent magnet question

So a nail takes away energy from a permanent magnet but an
electromagnet pulling a permanent magnet does not?

>>A magnet exerts a force. A magnet can attract things but it takes the
>>same amount of energy to remove those things so the nett output is 0.

>So I guess you would argue that a spring exerts force but never stores
>energy. Then it follows that it takes no energy to compress a spring.

A spring isn't a magnet. A spring stores energy by deformation.

A permanent magnet does not change in any way whether something is
stuck to it or not. Hence it cannot absorb or provide energy. This is
exactly what the over-unity tin-foil-hat people don't seem to
understand.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

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More options Apr 13 2012, 3:42 pm
Newsgroups: sci.electronics.design, sci.physics
From: HardySpicer <gyansor...@gmail.com>
Date: Fri, 13 Apr 2012 12:42:08 -0700 (PDT)
Local: Fri, Apr 13 2012 3:42 pm
Subject: Re: Energy in a permanent magnet question
On Apr 13, 11:35 pm, brent <buleg...@columbus.rr.com> wrote:

I have that paper and the first page is here

Hardy

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More options Apr 13 2012, 3:31 pm
Newsgroups: sci.electronics.design, sci.physics
From: HardySpicer <gyansor...@gmail.com>
Date: Fri, 13 Apr 2012 12:31:01 -0700 (PDT)
Local: Fri, Apr 13 2012 3:31 pm
Subject: Re: Energy in a permanent magnet question
On Apr 14, 3:34 am, John Larkin

I'm not talking perpetual motion, the energy presumably came from the
factory when it was magnetised.

Hardy