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Specific heat?

  1. Dec 6, 2003 #1
    specific heat????

    Hey guys….I need help with another problem.

    Q: Below are two sets of data from an experiment to determine the specific heat of a metal sample. For which mass will t the uncertainty n the specific heat be greater? Explain your answer. The uncertainty in all temperature measurements is +/- 1 degree C. And for all masses are +/- .1g. The specific heat of water is 1.0 cal/g degree C with negligible uncertainty.

    Metal Sample A:
    Initial temperature A----25 C
    Mass of metal A-------- 100g
    Initial Temp of water----100 C
    Mass of water-----200g
    Thermal Equilibrium temp of metal B in water---75 C

    Metal Sample B:
    Initial temp B----25C
    Mass of metal----100g
    Initial temp of water----100C
    Mass of water----200g
    Thermal Equilibrium temp of metal B in water---90C

    A: Q=m*C*(change temp)

    Metal A Q=(.1 +/-.0001kg)C(348+/-1K-298+/-1k)
    Metal A Q=5+/-.19716KgKC

    Metal B Q=(.1 +/-.0001kg)C(363+/-1K-298+/-1k)
    Metal B Q=6.5+/-.29705KgKC

    Now, I am stuck…I don’t know how to finish this problem. Can anyone help me??? Actually, I don’t even know if I am on the right track.

  2. jcsd
  3. Dec 7, 2003 #2
    I think this is an exercise in error propagation.
    If you have a function
    f = f(x, y, z),
    then the uncertainty is
    df = \sqrt{ (\frac{\partial f}{\partial x}dx)^2 + (\frac{\partial f}{\partial y}dy)^2 + (\frac{\partial f}{\partial z}dz)^2}.
  4. Dec 7, 2003 #3
    Is there a way to do work this problem with out calculus? Because my class is an algebra/trig based class. Thank you for your help.
  5. Dec 7, 2003 #4
    Well, in the 2 experiments all data are the same, except for the final temperature. So you could argue that the larger change in temperature corresponds to the smaller relative error.
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