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Old 03-05-2009, 08:32 PM   #1
theMan
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Default why does metal get hot when you bend it?

i was sitting here bending the handle of a fork back and fourth, and it got so hot after about 3 seconds it burned my finger. what causes this heat? friction inside the metal?
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Old 03-05-2009, 08:42 PM   #2
Brutus04
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Default why does metal get hot when you bend it?

Exactly; The atoms scrape against each other as the metal bends out of it's original shape. It's like rubbing your hands together except on a very smaller and more densely populated scale.
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Old 03-06-2009, 03:14 AM   #3
blahblah99
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Default why does metal get hot when you bend it?

First law of thermodynamics.
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Old 03-06-2009, 03:39 AM   #4
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: blahblah99
First law of thermodynamics.
is you don't talk about thermodynamics.
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Old 03-06-2009, 06:59 AM   #5
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Default why does metal get hot when you bend it?

Input work by bending/stretching and you increase the internal (strain) energy of the fork. Viscous losses in the fork convert the energy to heat, while some of them are stored as elastic strain energy which will recover some of the strain you impart.
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Old 03-06-2009, 11:46 AM   #6
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Default why does metal get hot when you bend it?

Conservation of energy.

Energy used to bend the fork gets converted into heat.

Chemical energy from ingested food yields glucose,
which is converted to ATP,
which is converted to ADP and release energy,
which allows release of ionic calcium in the muscle,
which interact with myofibrils to induce contraction and produce kinetic energy,
which gets converted to kinetic energy applied to the metal thereby bending it,
which gets converted to thermal energy in the metal.

Total efficiency to produce heat from chemical energy through this process... less than 5%?!?
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Old 03-06-2009, 10:05 PM   #7
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: Born2bwire
Quote:
Originally posted by: blahblah99
First law of thermodynamics.
is you don't talk about thermodynamics.
In this house, we obey the laws of thermodynamics.
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Old 03-07-2009, 09:35 AM   #8
polarbear6
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Default why does metal get hot when you bend it?

two words
tangential stress
simple mechanics

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Old 03-07-2009, 08:16 PM   #9
mindless1
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Default why does metal get hot when you bend it?

Your will caused the heat, friction was only a side-effect. If you keep it up you will be kicked out of our restaurant.
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Old 03-10-2009, 10:27 AM   #10
JTsyo
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: Born2bwire
Quote:
Originally posted by: blahblah99
First law of thermodynamics.
is you don't talk about thermodynamics.
There is no fork.
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Old 03-19-2009, 11:54 AM   #11
Coca Cola
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: JTsyo
Quote:
Originally posted by: Born2bwire
Quote:
Originally posted by: blahblah99
First law of thermodynamics.
is you don't talk about thermodynamics.
There is no fork.

There is no fork?




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Old 03-19-2009, 03:39 PM   #12
Kraeoss
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Default why does metal get hot when you bend it?

upon concentrating on the fork realise that it's not the fork that bends but you and you burned your self with that realization......
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Old 03-26-2009, 10:45 AM   #13
Jahee
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: ganesh1
two words
tangential stress
simple mechanics
Real helpful..
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Old 03-26-2009, 04:34 PM   #14
bobsmith1492
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Default why does metal get hot when you bend it?

Quote:
Originally posted by: Jahee
Quote:
Originally posted by: ganesh1
two words
tangential stress
simple mechanics
Real helpful..
That's four words...

One word:

Friction
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