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Homework Help: Help mechanics

  1. Feb 14, 2010 #1

    nna

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    I hope somebody can help me.. this is the problem i have to proof that if A is a constant vector then I can write its derivate as dA/dt = \omega x A.. where \omega is a vector, and the "x" is the cross product
     
  2. jcsd
  3. Feb 14, 2010 #2

    tiny-tim

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    Welcome to PF!

    Hi nna! Welcome to PF! :smile:

    (have an omega: ω :wink:)
    (You mean "if A is constant in magnitude".)

    Hint: if the magnitude is constant, then so is the magnitude squared, which is A.A. :wink:
     
  4. Feb 14, 2010 #3

    nna

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    Sorry :( but I don't understand how that helps...
     
  5. Feb 14, 2010 #4

    tiny-tim

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    Differentiate it …

    what do you get? :smile:
     
  6. Feb 14, 2010 #5

    nna

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    ok ok thank you so much!!! it really helps... jaja it was very easy sorry
     
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