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Energy conservation in Acid

  1. Mar 18, 2010 #1
    Case:1 I have one iron spring. I compress it gives potential energy E= ½* K*x2 & bind it by glass wire which is not melted in acid. Now I put this spring in acid & it melted completely, So where the potential energy gone?

    Case:2 I put one magnet in glass vessel & hold it in vessel by some mechanical means. I put another magnet outside of vessel in such a way that there is a repulsive force between them & so both magnet possesses potential energy w.r.t. each other. Now I pour acid in vessel & magnet inside vessel is melted, So where the potential energy gone?

    Case:3 I charge capacitor & break it. Both the charged plate taking outside carefully so it not get discharged. Previously the energy which is in the dielectric media, now where is that energy? If I destroy both the plate of capacitor by throwing it into acid OR furnace, How the energy will conserve which I have given to charge the capacitor?
    Please for giving answer take suitable acid & material.
    Please give explanation from microscopic point of view also, so I can understand better.
     
  2. jcsd
  3. Mar 18, 2010 #2

    Borek

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    Staff: Mentor

    Final temperatures of solutions should differ.

    Case 3: was it easy to pull the plate apart?

    Note: metal doesn't melt in acid, it dissolves.
     
    Last edited by a moderator: Aug 13, 2013
  4. Mar 18, 2010 #3

    Dale

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    Borek is correct theoretically, but from a practical standpoint you will get stress corrosion cracking which will break the spring and mechanically release the remaining potential energy long before it dissolves.
     
  5. Mar 19, 2010 #4

    Borek

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    Heating the solution :tongue2:
     
    Last edited by a moderator: Aug 13, 2013
  6. Mar 19, 2010 #5
     
  7. Mar 19, 2010 #6
    Hello, Borek, Dalespam.
    Thank you for giving reply.
     
  8. Mar 19, 2010 #7

    Borek

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    You have missed the point. You need to apply some force to pull apart charged plate, don't you? It is not different from pulling apart two charges.
     
    Last edited by a moderator: Aug 13, 2013
  9. Mar 19, 2010 #8
    OK, it required force to pull apart & this additional energy which I give plate to pull apart is giving higher increase in temperature then theoretical calculation in which I only take electrical energy for calculation of rise in temp.
    thank you.
     
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