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Homework Help: Modelling Problem

  1. Oct 27, 2005 #1
    I'm dong a question that involves a sink. The aim is to determine the dimensions of the sink (width and length) which will provide the greated cross-sectional area by modelling using an equation. Here's the catch: you are only allowed a sheet of stainless steel that it 60cm wide and a 5cm overlap has to be allowed for on either side of the sink.

    So far i've figured this:
    when:
    c=cross-sectional ares
    a=area
    l=length
    w=width

    a= l x w
    c=a
    so c= l x w

    w=60-(10+2L)

    therefore:
    c= L[60-(10+2L)]
    c=60L-10L+2L^2

    etc etc. when applying this formula like this:

    L = c/w
    L = L[60(10+2L)] / 60(10+2L)

    eventually L turns out to be 0 (duh i didnt give it a value)
    But here comes my question: is there a flaw in my formula or am i completely off-track? please help!!!
     
  2. jcsd
  3. Oct 27, 2005 #2
    Here is the picture...
     

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  4. Oct 28, 2005 #3

    Tide

    User Avatar
    Science Advisor
    Homework Helper

    Harriet,

    Perhaps you would clarify exactly what problem you are attempting to solve. I don't understand what you're looking for from what you wrote.
     
  5. Oct 28, 2005 #4
    lets see what we have

    2l + w + 10 = 60

    a = l * w

    w = 50 - 2l

    so a = (50 - 2l) * l

    da/dl = 50 - 4l

    set = to 0

    50 - 4 * l = 0

    l = 12.5

    plug it in the area equation

    50(12.5) - 2(12.5) ^2 = 312.5

    you can do the rest yes
     
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