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Posers and Puzzles

Posers and Puzzles

  1. Subscriber sonhouse
    Fast and Curious
    25 Dec '05 20:56
    Just wondered, obviously with a dvm you can make a good prediction
    of the life left in a battery, like the AA cells for instance. Is it possible
    to figure out the charge left if you had a sufficiently accurate
    scale? Like Picograms or some such. Wouldn't a battery get a tiny
    bit lighter as it used up charge? Hmm, its hermetically sealed mostly
    but maybe gasses could escape. What do you all think?
  2. 27 Dec '05 03:55 / 1 edit
    Originally posted by sonhouse
    Just wondered, obviously with a dvm you can make a good prediction
    of the life left in a battery, like the AA cells for instance. Is it possible
    to figure out the charge left if you had a sufficiently accurate
    scale? Like Picograms or some such. Wouldn't a battery get a tiny
    bit lighter as it used up charge? Hmm, its hermetically sealed mostly
    but maybe gasses could escape. What do you all think?
    Practical application of knowledge is for the birds.
  3. Standard member XanthosNZ
    Cancerous Bus Crash
    27 Dec '05 04:44
    Originally posted by sonhouse
    Just wondered, obviously with a dvm you can make a good prediction
    of the life left in a battery, like the AA cells for instance. Is it possible
    to figure out the charge left if you had a sufficiently accurate
    scale? Like Picograms or some such. Wouldn't a battery get a tiny
    bit lighter as it used up charge? Hmm, its hermetically sealed mostly
    but maybe gasses could escape. What do you all think?
    As far as I know most batteries (NiMH, NiCad, Li-Ion) aren't giving off gases as they are used. If this is true then conservation of matter states that the weight won't change as charge does.
  4. Standard member Alcra
    Lazy Sod
    27 Dec '05 10:29
    Originally posted by XanthosNZ
    As far as I know most batteries (NiMH, NiCad, Li-Ion) aren't giving off gases as they are used. If this is true then conservation of matter states that the weight won't change as charge does.
    Do electrons not "move out" of the battery? If so, a tiny loss of mass would occur?
  5. Standard member XanthosNZ
    Cancerous Bus Crash
    27 Dec '05 12:07
    Originally posted by Alcra
    Do electrons not "move out" of the battery? If so, a tiny loss of mass would occur?
    They also 'move into' the battery at the same rate, conservation of charge and all that.
  6. Subscriber sonhouse
    Fast and Curious
    28 Dec '05 17:29
    Originally posted by XanthosNZ
    They also 'move into' the battery at the same rate, conservation of charge and all that.
    Thats for sure! Maybe one or two strays would go in or out but I don't
    think we can weigh one electron yet. If there is energy used,
    molecules will swap mass and mass is usually lost. If it isn't, THAT
    is breaking the law of conservation of energy. Just like a fusion
    reaction, some atoms whack together fiercely enough to fuse but
    some of that energy is given off in various forms and the system
    losses mass, even if say an electron is converted to a photon,
    the mass goes down because the electron is now a photon which is
    massless but the total energy will be conserved, ala E=MC^2.
  7. Donation richjohnson
    TANSTAAFL
    28 Dec '05 22:46
    Originally posted by sonhouse
    Thats for sure! Maybe one or two strays would go in or out but I don't
    think we can weigh one electron yet. If there is energy used,
    molecules will swap mass and mass is usually lost. If it isn't, THAT
    is breaking the law of conservation of energy. Just like a fusion
    reaction, some atoms whack together fiercely enough to fuse but
    some of that energy ...[text shortened]... lectron is now a photon which is
    massless but the total energy will be conserved, ala E=MC^2.
    I could be wrong, but I don't think any mass is converted to energy in batteries. Energy is conserved because, for each unit of electrical energy produced, the battery loses a corresponding amount of chemical potential energy.
  8. Standard member XanthosNZ
    Cancerous Bus Crash
    29 Dec '05 01:42
    Originally posted by richjohnson
    I could be wrong, but I don't think any mass is converted to energy in batteries. Energy is conserved because, for each unit of electrical energy produced, the battery loses a corresponding amount of chemical potential energy.
    This is correct.

    A ball would gain a lot of energy if you took it to the top of a building. It doesn't lose mass though.
  9. Standard member Bowmann
    Non-Subscriber
    29 Dec '05 02:26
    Potential energy is nonsense.
  10. Subscriber sonhouse
    Fast and Curious
    29 Dec '05 14:17
    Originally posted by XanthosNZ
    This is correct.

    A ball would gain a lot of energy if you took it to the top of a building. It doesn't lose mass though.
    Good point, relativistic effects aside.
  11. Subscriber sonhouse
    Fast and Curious
    29 Dec '05 14:18
    Originally posted by Bowmann
    Potential energy is nonsense.
    Useful nonsense though.
  12. Subscriber Suzianne
    Misfit Queen
    02 Jan '06 11:41
    Originally posted by Bowmann
    Potential energy is nonsense.
    So kinetic energy is nonsense as well?