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What is (KE1-KE2)/KE2=M/(M+m)

  1. Nov 7, 2005 #1
    hi i have a question. What does this equation mean??
    (KE1-KE2)/KE2=M/(M+m) and how is it derived??

    I dont understand. Please help me.
  2. jcsd
  3. Nov 7, 2005 #2
    Could you give more information? For instance does this have anything to do with planets, pendulums, levers, or pullies?
  4. Nov 7, 2005 #3


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    What does M and m represent? Is this molecular kinetic theory? (i.e. M is mass of volume V of gas and m is the mass of one molecule) or is it mechanics?
    Last edited: Nov 7, 2005
  5. Nov 7, 2005 #4

    the question has to do with collision..the conservation of energy and momentum. the formula has to do with the theoretical fractional energy loss
    the letters "f" and "i" are subscript. (KEi-KEf)/KEi=M(M+m)
    The M and m are masses. I dont know how to give anymore information because thats about all i know. please help.. anyone who understands these things...
  6. Nov 8, 2005 #5
    It looks like you have two objects in a system and this systme has an initial kinetic energy of [tex]KE_i[/tex] and a final kinetic energy of [tex]KE_f[/tex]. When v<<c, [tex]KE= \frac{1}{2}mv^2[/tex]. When v is not v<<c then [tex]KE= \frac{mc^2}{\sqrt{1-v^2/c^2}}-mc^2[/tex].

    Some of the kinetic energy will be lost if the collision is inelastic.
    Last edited: Nov 8, 2005
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