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Homework Help: Thermodynamics, cars colliding

  1. Feb 24, 2009 #1
    1. The problem statement, all variables and given/known data

    Two cars collide head on while each is traveling at 80 km/hr. Suppose all their kinetic energy is transformed into the thermal energy of the wrecks. What is the temperature increase of each car? (Assume each car's specific heat is that of iron)

    2. Relevant equations

    K = .5mv^2
    Q = cm(delta T)
    iron specific heat = .449 J/(g*K)

    3. The attempt at a solution

    K = 2(.5m(22.2)^2) = 492.8m

    (converted 80 km/hr to m/s)

    Q = 492.8m = (.449)(2m)(delta T)
    delta T = 548.8 K


    Which is the wrong answer. I dont know what i am doing wrong. Can someone please help me. Thanks
     
  2. jcsd
  3. Feb 24, 2009 #2
    Got, it. Just needed to convert iron specific heat from J/(g*K) to J/(kg*K), so delta T is just .549
     
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