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Homework Help: Differential free falling bodies

  1. Feb 22, 2009 #1
    (i) how you solved this problem,

    An object of mass 10 kg is dropped from a great height. (a) If the object is subjected to air resistance equivalent to 10 times the instantaneous velocity, find the velocity. (b) How far does the object drop after 5 sec?

    (ii) what you got as a solution,

    Don't know how to start. But i know you use differential equations.

    (iii) why you think that is wrong.
  2. jcsd
  3. Feb 22, 2009 #2


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    try writing what the force or acceleration is at any given instant...
  4. Feb 22, 2009 #3
    Would it be 10(dv/dt)=98-10v?
  5. Feb 23, 2009 #4


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    looks ok to me, now mass drops out of the equation, as it mulitplies every term..

    now you can look at solving, probably a good place for separation of variables - what do you think?
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