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Homework Help: Thermal physics

  1. Nov 5, 2004 #1
    I can't solve this problem. Could anyone help me?
    A piece of metal with a mass of 2kg and specific heat of 200J/kg C is initially at a temperature of 120 C. The metal is placed into an insulated container that contains a liquid of mass 4kg, a specific heat of 600J/kg C, and an initial temperature of 20C.
    I am using equation
    Mm * Cm(Tf-Ti)=Ml*Cl(Tf-Ti)
    2*200*(Tf-120)=4*600*(Tf-20)
    (Tf-120)=6*(Tf-20)
    Tf-120 = 6Tf-120
    Tf=6Tf
    Where did I make a mistake?
    Thanks
     
  2. jcsd
  3. Nov 5, 2004 #2
    In the first formula you use there should be a minus sign on one of the sides. This is an energy equation; energy is conserved so the amount of heat that the metal loses (-) is gained (+) by the liquid...
     
  4. Nov 5, 2004 #3
    ohh You are right. Thank you very much.
     
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