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Homework Help: Thermal physics calculations

  1. Jul 23, 2008 #1
    Hi..i was trying out some calculations i found on some site as practice for my exam this Friday and realised that i dont understand at all..
    Everytime i tried something..my answers were wrong..


    1. How much heat energy is needed to heat 4 kg of aluminium by 8 (degrees)C?

    The answer:

    1. Energy = mC(delta)θ = 4 x 1200 x 8 = 38400 J

    I dont understand where the 1200 came from..

    Can anybody give me links to thermal physics and general physics notes and/or worked examples for me to try out?
  2. jcsd
  3. Jul 23, 2008 #2


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    Staff Emeritus
    Science Advisor

    It would help if one would write units with the numbers in a problem.

    Energy = mC(delta)θ, where m is the mass (in this case 4 kg), C is specific heat (which is unique or specific to a material which would be in units of J/kg-K), and θ would be the temperature (in K or °C, and not to be confuse with an angle). Some people use T for temperature.

    Here is a good site for some basic physics - http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

    and for the problem at hand - http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html

    Table of specific heats - http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html#c1
    Cp = 900 J/kg-K for Al in this table.

    Please expend some effort and review the notes on Hyperphysics.

    Thank you. :smile:
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