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Math Help - Calc 2: Find the work W required to pump the water out ....

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    Calc 2: Find the work W required to pump the water out ....

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  2. #2
    MHF Contributor Calculus26's Avatar
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    The cross-sections are rectangles all of which are 12 m long and have variable width.

    To find the width as a function of y --the height above thr ground use similar triangles.

    The distance a cross -section is pumped is 7 -y

    The int limits are 0 to 4

    See attachment
    Attached Thumbnails Attached Thumbnails Calc 2: Find the work W required to pump the water out ....-work3.jpg  
    Last edited by Calculus26; January 29th 2010 at 12:46 PM.
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  3. #3
    MHF Contributor ebaines's Avatar
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    Don't forget to multiply by g times the densiy of water, which is approximateley 100 Kg/m^3. This gets you the answer in terms of kg-m^2/s^2, or Joules.
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    MHF Contributor Calculus26's Avatar
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    Thanks--- I was thinking density =1kg/L which is true but as you pointed out the units would have been off.

    1kg/L tranlsates to 1000kg/m^3 not 100
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  5. #5
    MHF Contributor ebaines's Avatar
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    Quote Originally Posted by Calculus26 View Post
    1kg/L tranlsates to 1000kg/m^3 not 100
    Oops! Yes - thanks for catching that!
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  6. #6
    MHF Contributor Calculus26's Avatar
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    The following attachment reflects the changes-- thanks again
    Attached Thumbnails Attached Thumbnails Calc 2: Find the work W required to pump the water out ....-work3.jpg  
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