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Volume Of solids question help

  1. Sep 2, 2011 #1
    Volume Of solids question help!!

    1. The problem statement, all variables and given/known data

    i) find the area enclosed by the curves y=x^1/2 and y=x^4
    ii)find the volume of the solid when the area in part (i) is rotated about the the line x=2

    2. Relevant equations
    V=PI*y^2dx


    3. The attempt at a solution
    wel the area is simple integral 0 to1 root x -x^.5 and i got 7/15

    but im not sure how to calculate the volume about x=2
     
  2. jcsd
  3. Sep 2, 2011 #2

    tiny-tim

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    hi joe007! :smile:
    slice the volume into horizontal "washers" of height dy, and integrate :wink:
     
  4. Sep 2, 2011 #3

    HallsofIvy

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    Re: Volume Of solids question help!!

    Equivalent to "washers": Use "disks" to find the volume when [itex]y= x^{1/2}[/itex] is rotated around the x-axis, then use "disks" to find the volume when [itex]y= x^4[/itex] is rotated around the x-axis, and subtract.
     
  5. Sep 2, 2011 #4
    Re: Volume Of solids question help!!

    so its V=2PI* (integral 0 to 2) (x-2)x^0.5 -(x-2)x^4 dx
     
  6. Sep 2, 2011 #5
    Re: Volume Of solids question help!!

    i think it should be from 0 to 1
     
  7. Sep 2, 2011 #6

    SammyS

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    Re: Volume Of solids question help!!

    Correct !
     
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