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How do I model the falling of a skydiver using a DF?

  1. Oct 14, 2009 #1
    • I'm given the initial conditions vnot=0m/s, hnot=3000m, and tnot=0s

      After 35 seconds of freefall, the chute opens.

      I am to write a piece-wise define diff equation for the rate of change of velocity, with the two pieces t<35 and t >_35.

      I am not given a mass.

    Now, I understand how to start at http://media.wiley.com/Lux/97/19597.nce030.jpg

    And how to go to http://media.wiley.com/Lux/00/19600.nce033.jpg. (where b=k/m)

    This represents the sky diver initially falling without a parachute.

    And this with a chute: http://media.wiley.com/Lux/03/19603.nce036.jpg

    Three questions:

    1.) Since I'm not given a mass, and are supposed to graph both solutions, how do I do this?

    2.) Do I use the initial height anywhere in this equation?

    3.) Once I solve each equation, what do I do with the piecewise part numbers? ( t<35 and t >_35.)

    Thanks for any help
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Oct 14, 2009 #2
    Just write m in your derivations for the mass. And marvellously, m cancels out. Legend says that Galilleo dropped two different weights from a tower to demonstrate this fact that the mass doesn't matter...
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