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Calculating velocity in regards to the mass and kinetic energy of an object

  1. Aug 10, 2012 #1
    1. The problem statement, all variables and given/known data

    How fast is a baseball with a mass of 145 g travelling if it has 94 J of kinetic energy?


    2. Relevant equations

    m = 145 g or 0.0145 kg
    Ek = 94 J
    v = ?

    v = √2Ek/m



    3. The attempt at a solution

    I get...
    v = √2(94)/0.0145 kg
    v = √12966
    v = 114

    But my book says it should be 36 m/s. What am I doing wrong?

    It also mentions that I need to recall that 1 J = 1 kg . m^2/s^2 but I am unsure how to incorporate this into the equation or if it is even necessary.
     
  2. jcsd
  3. Aug 10, 2012 #2
    Your mass should be .145 kg.
     
  4. Aug 10, 2012 #3
    Your mass should be 0.145 kg and not 0.0145kg
     
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