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How to integrate (dx/dt ) dx?

  1. Aug 15, 2015 #1
    Good Night,

    Can someone please tell me how to do: ∫ b (dx/dt) ⋅ dx ?

    Like in the work done by a force which is proportional to the velocity (like drag). I tried to change dx to v dt but couldn´t go much further.

    Thank you in advance.
     
  2. jcsd
  3. Aug 15, 2015 #2

    andrewkirk

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    If you write ##v=\frac{dx}{dt}## then you have ##dx=v\,dt## and you can write your equation as ##\int b\,v^2 dt##.
     
  4. Aug 16, 2015 #3

    Orodruin

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    Note that it is sometimes easier to express ##dx/dt## as a function of ##x## rather than ##t##. In these cases, you can simply integrate that function. You really cannot get any further without having a specific integral to do. Note that such a problem should be posted in the homework forums with the template properly filled in, including your own attempt and the full problem statement.
     
  5. Aug 16, 2015 #4
    Thank you very much
     
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