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Homework Help: Temperature and Heat

  1. Jan 26, 2005 #1
    At a fabrication plant, a hot metal forging has a mass of 76 kg and a specific heat capacity of 430 J/(kg · °C). To harden it, the forging is immersed in 710 kg of oil that has a temperature of 32°C and a specific heat capacity of 2900 J/(kg · °C). The final temperature of the oil and forging at thermal equilibrium is 46°C. Assuming that heat flows only between the forging and the oil, determine the initial temperature of the forging.

    (the sub 1 refers to the metal, the o refers to the oil)
    what I assumed I would do for this is say:
    [tex]m_{1}c_{1}T_{1}=m_{o}c_{o}(\Delta T_{o} - 46^o C)[/tex]
    [tex]T_{1}=\frac{m_{o}c_{o}(\Delta T_{o} - 46^o C)}{m_{1}c_{1}}[/tex]

    That, unfortunately, is wrong...
    any help would be great ... this is due in an hour.

    I also have a problem with this question:
    A precious-stone dealer wishes to find the specific heat capacity of a 0.032 kg gemstone. The specimen is heated to 95.0°C and then placed in a 0.10 kg copper vessel that contains 0.083 kg of water at equilibrium at 25.0°C. The loss of heat to the external environment is negligible. When equilibrium is established, the temperature is 28.5°C. What is the specific heat capacity of the specimen?

    for this one i used the same
    [tex]c_{1}m_{1}\Delta T_{1}=c_{2}m_{2}\Delta T_{2}[/tex]
    formula, but it was wrong again... Am I even using the correct formula? Thanks!
    Last edited: Jan 26, 2005
  2. jcsd
  3. Jan 27, 2005 #2


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    Homework Helper

    For the first problem,u assumed wrongly that the temperature of the metal is kept constant at 46°...Redo the thinking.

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