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Homework Help: Kinetic energy?

  1. Oct 16, 2007 #1
    kinetic energy????

    a continent is 4200 km on a side and 32 km deep

    its mass density is 2680 kg/m^3
    it is moving at an avg speed of 4.8cm/year

    what is its mass? answer in units of J

    what is its kinetic energy? answer in units of J

    a jogger with mass 75kg has the same kinetic energy as the continent... what is his velocity?? answer in units of m/s

    i know the KE equation is KE = .5 * m * V^2

    i am stuck on what my steps are with this problem... i know if i solve the first part the 2nd and 3rd parts will be easy becuz i plug them into the KE equation
  2. jcsd
  3. Oct 16, 2007 #2
    to find the mass of the contintent i would take

    Density = mass/volume

    2680kg/m^3 = mass / (42000000m * 4200000m * 32000m)

    and then solve for mass and that gives me the mass in kg????
  4. Oct 16, 2007 #3
    yes...exactly....then plug in for KE equation
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