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Homework Help: Differentiating volume of a cylinder

  1. May 22, 2006 #1
    1. differentiate the volume of a cylinder with v respect to h

    my working out:
    v= πr^2h
    dV\dh= 2πr

    n da answer is not right
    how do i make da "h" remains in da equation?
    could some one please help me?
    thank you
     
  2. jcsd
  3. May 22, 2006 #2
    Hint:Note that r is a constant
     
  4. May 22, 2006 #3
    i am not sure what you mean though

    do u mean that dV\dh= πh??? instead of 2πr
     
  5. May 22, 2006 #4

    J77

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    What you've done is differentiate with respect to h and then with respect to r (or r then h) to get at [tex]2\pi r[/tex].

    You can leave the r alone and just diff. w.r.t. h
     
  6. May 22, 2006 #5

    HallsofIvy

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    Science Advisor

    If "A" is a constant and v(h)= Ah, what is dv/dh?

    If [itex]v(h)= \pi r^2h[/itex], what is the constant "A"?
     
  7. May 23, 2006 #6
    do i apply the product rule to find dv/dh?
     
  8. May 23, 2006 #7
    No,
    Read Hallsofivy's post carefully.
     
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