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Homework Help: Work to stop a car

  1. Nov 13, 2007 #1


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    1. The problem statement, all variables and given/known data

    How much work must be done to stop a 1100 kg car traveling at 118 km/hr?

    2. Relevant equations
    Ei + W= Ef
    KE= 1/2mv^2

    3. The attempt at a solution

    KE= 1/2mv^2

    118kmx1000m/360s= 327.78

    327.78^2= 107437.76

    107437.76x1100= 118181537.9

    118181537.9/2 = -5.91x10^7

    thanks for any help
  2. jcsd
  3. Nov 13, 2007 #2

    Doc Al

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    Staff: Mentor

    Recheck that conversion: How many seconds in an hour?
  4. Nov 13, 2007 #3
    do KE = 1/2 (1100 kg)(118*(1000/3600))^2
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