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Homework Help: Parachutist jumping from plane Conservation of Energy

  1. Feb 26, 2009 #1
    1. The problem statement, all variables and given/known data

    A parachutist with mass m = 70 kg jumps from an airplane traveling at a speed v = 100 km/h at a height H = 2500 m and lands with a speed vf = 5.00 m/s. Use the “conservation of energy strategy” to calculate the change in internal energy of the system from just after the jump until just before landing. (1E6)

    2. Relevant equations

    PE+KE=PE[f]+KE[f]

    3. The attempt at a solution

    I'm thinking that where it talks about the airplane traveling at 100 km/h makes no difference in this problem. So the actual initial velocity would be vi=0km/h then I think I would calculate the velocity without Air Resistance and then factor in the difference of speed. Am I headed in the right direction.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Feb 26, 2009 #2

    Delphi51

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    He will have speed 100 km/h initially. Don't forget to convert to m/s.
     
  4. Feb 26, 2009 #3
    Why though? is the plane traveling downward?
     
  5. Feb 26, 2009 #4

    Delphi51

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    Homework Helper

    Direction is not important in calculating energy. The parachutist will have a horizontal speed of 100 - same as the plane - when he first lets go.
     
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