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Integral dw/rdr

  1. Jun 23, 2008 #1
    Plz explain me how can i integrate dw/rdr
  2. jcsd
  3. Jun 23, 2008 #2
    plz help me with this..
  4. Jun 23, 2008 #3


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    Could you perhaps explain you question further?
  5. Jun 23, 2008 #4
    w is a function of r and i need to integrate dw/rdr with respect to r
  6. Jun 23, 2008 #5


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    you mean you want to find

    [tex]\int \frac{1}{r} \frac{dw}{dr} dr[/tex]

  7. Jun 23, 2008 #6
    Ya exactly..
  8. Jun 23, 2008 #7
    I was trying it by using by parts.. By taking 1/r as the first function. But with that i m getting the answer zero..
  9. Jun 23, 2008 #8


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    Do you happen to know what dw/dr is ?
  10. Jun 23, 2008 #9
    w is a function of r here.. So it can be written as dw(r)/dr
  11. Jun 24, 2008 #10


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    I'm sorry but this just seems silly. It's like asking, how do I do the integral [tex]\int{f(x)dx}[/tex]. The answer to this question will clearly depend on what f(x) is. Here, the answer to your question will depend on what kind of function w(r) is. So unless you give us more information, I don't think we can help you.
  12. Jun 24, 2008 #11
    Actually I am calculating the value of w(r) from a differential equation.. And in satisfying the boundary conditions I need to know that integral to calculate the valuues of constants. As of now w(r) is unknown.
  13. Jun 24, 2008 #12


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    Then I suggest you post the question. We won't know how to help if we don't know exactly what the question is asking for.
  14. Jun 24, 2008 #13


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    Going back to the original question, which I suspect is NOT the question you are really asking,

    [tex]\int (dw/dr)dr= w(r)+ C[tex]
    where C is an arbitrary constant, by the fundamental theorem of calculus.
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