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Homework Help: Kinetic Energy

  1. Dec 8, 2008 #1
    A car has the kinetic energy of 432000 Joules when traveling at a speed of 42 m/s.

    What is its mass? (Kg)

    I know that K.E. = (1/2)(Mass)(Velocity squared)

    So the equation reads 432000 = (1/2)(42 squared)(M)
    I got an answer of 150 but my online program told me it was wrong.

    Do I need to convert units somewhere?
  2. jcsd
  3. Dec 8, 2008 #2


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    Homework Helper

    No. Everything is in SI units. I think you just made a typo in your calculator.
  4. Dec 8, 2008 #3
    when I did it, I had an answer about 3 times bigger than yours. Perhaps check your math?
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