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Forces and kinetic energy problem

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data
    Shawn and his bike have a total mass of 43.5 kg. Shawn rides his bike 1.3 km in 10.4 min at a constant velocity.
    The acceleration of gravity is 9.8 m/s^2
    What is Shawn's kinetic energy?


    2. Relevant equations
    F = ma
    Ff = u * Fn
    Fn = mg
    avgV = x/t
    x = 1/2(Vf + Vi)t


    3. The attempt at a solution

    ok so I converted km to m and min to s:
    x = 1300m
    t = 624s
    and then i used avgV = x/t so avgV = ~2.08333 m/s

    i have no idea what kinetic energy is, this hasn't been covered in class yet but I wanted to get ahead because I think I am coming down with the flu. The answer to the problem is supposed to be 94.4014 J but I have no idea how to set this problem up to get this. Please help me! Thanks.
     
  2. jcsd
  3. Oct 26, 2009 #2

    rl.bhat

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    Homework Helper

    The kinetic energy = 1/2*m*v^2
     
  4. Oct 26, 2009 #3
    THAAATTSS what i needed ooohhh maaann thanx rl.bhat!
    so it would be (0.5)(43.5)(2.08333)^2 = 45.3124 J

    thanks again!
     
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