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Homework Help: Calculating heat energy

  1. Oct 13, 2005 #1
    Calculating heat energy....

    Q. #1
    A 16 kg object is dropped from a height of 25 m and strikes the ground with a speed of 18 m/s. How much heat energy was produced during the fall?

    Choices
    A) 0 J
    B) 2 600 J
    C) 1 300 J
    D) 3 900 J

    Well,according to my calculation, the average acceleration was about 6.48m/s, which means 3.32N/kg acted as air friction.

    And I'm lost from there.

    Help will be greatly appreciated!
     
  2. jcsd
  3. Oct 13, 2005 #2

    Tide

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    HINT: Energy is conserved! :)
     
  4. Oct 13, 2005 #3

    Pyrrhus

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    Like Tide said remember

    [tex] \Delta K + \Delta U = W_{friction} [/tex]
     
  5. Oct 13, 2005 #4

    Andrew Mason

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    You don't have to work out force or average speed. Just use potential energy: mgh.

    AM
     
  6. Oct 15, 2005 #5
    ouch, I learned that a year ago and I have no idea how can I forget such thing ...Thx!
     
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