Drop a ball - where does the energy go?

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  • #1
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Hi -

If I lift a bowling ball in the air, so that it has potential energy, then drop it on the dirt, it makes a sound and a dent. Where did all the energy go? It did not all go to sound, since there's a dent, right? A small bit went to heat... what else?

Thanks
 

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  • #2
A.T.
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A small bit went to heat...
All of it goes to heat, after a while.
 
  • #3
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The bit that went to heat aint small. Do the following experiment. Ask someone to hold a piece of paper up in the air for you and Bang two pieces of steel together making sure the paper is caught in between them. There should be a burnt spot on the paper afterwards.
 
  • #4
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Thanks
 
  • #5
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That's interesting, dauto. If I'm lost in Alaska and about to freeze, and find two hammers and some paper, is it possible that I could start a fire to save my life?
 
  • #6
HallsofIvy
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Hi -

If I lift a bowling ball in the air, so that it has potential energy, then drop it on the dirt, it makes a sound and a dent. Where did all the energy go? It did not all go to sound, since there's a dent, right? A small bit went to heat... what else?

Thanks
Initially some energy goes into the kinetic energy of the little pieces of dirt that are moved away to make that 'dent'. Of course, all of those eventually (very quickly) stop because of friction- which is the same as saying the energy becomes heat energy. (In the long scale 'eventually' all energy becomes heat.)
 
  • #7
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That's interesting, dauto. If I'm lost in Alaska and about to freeze, and find two hammers and some paper, is it possible that I could start a fire to save my life?

Unlikely. The paper burns but you don't get a flame that way. The heat dissipates to quickly
 
  • #8
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Unlikely. The paper burns but you don't get a flame that way. The heat dissipates to quickly

Hmmm... What if you lightly soaked the paper in alcohol first? Anyone want to give that a try?
 
  • #9
phinds
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Hmmm... What if you lightly soaked the paper in alcohol first? Anyone want to give that a try?

Nah, you do it ... I'm drinking my alcohol :smile:
 
  • #10
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Hmmm... What if you lightly soaked the paper in alcohol first? Anyone want to give that a try?

As mentioned by dauto the heat dissipates very fast, I don't think alcohol will be effective since the temperature will go below the flash point even before oxygen is supplied.
 
  • #11
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Well, we won't really know until some idiot tries it, right?

Maybe I'll give it a shot tomorrow...
 
  • #12
Lok
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Heat is not the only energy transformation. The dent means plastic deformation, so the breaking or tensing material. So energy gets stored in material induced stresses and get's absorbed by the breaking of chemical or physical bonds. The plastic deformation energy is not all transformable to heat and is very material dependent.
 

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