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Homework Help: Force problem (whoever answers correct will be rewarded a cookie !)

  1. Apr 24, 2010 #1
    1. The problem statement, all variables and given/known data
    Train with mass m=6*105kg moves with a constant speed of v=54km/h.After the engine shut down ,train stops in t=40s .Find the average force train performs before engine shut down?


    2. Relevant equations
    I think its asking for Force ? if yes will this equation below do ?


    3. The attempt at a solution

    F=m/t*(mv2/2)

    I could be so wrong like GIGANTIC WRONG please braniacs reveal your wisdom on this very rough moment for me !
     
  2. jcsd
  3. Apr 24, 2010 #2

    ideasrule

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    Homework Helper

    What's F=m/t*(mv2/2)? Force certainly isn't equal to power times mass.

    This is just a kinematics problem. Can you find the train's acceleration? If so, you can find the force using F=ma.
     
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