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    hello, i need help with this question. i have answered part a with \frac{dA}{dt} = a^2 but am not sure if this part is correct. i am also having trouble setting up a differential equation for the second part of the question, could anybody give me any tip? thanks

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\dfrac{dA}{dt} \neq A^2

    But, rather:
    

\dfrac{dA}{dt} \propto A^2

    So:
    

\dfrac{dA}{dt} = k A^2

    Then use the information in part ii to determine k.
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    (Original post by Qwertish)
    

\dfrac{dA}{dt} \neq A^2

    But, rather:
    

\dfrac{dA}{dt} \propto A^2

    So:
    

\dfrac{dA}{dt} = k A^2

    Then use the information in part ii to determine k.
    right, thankyou. would then  1 = k 10^2 or  1000 = k 10^2 ?
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\dfrac{2000-1000}{2-1} = 2000^2k

    I think that should be right. Remember that dA and dt are changes, not fixed values.

    EDIT: This is wrong. Ignore it.
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    (Original post by Qwertish)
    

\dfrac{2000-1000}{2-1} = 2000^2k

    I think that should be right. Remember that dA and dt are changes, not fixed values.
    okay, i have identified k as being  \frac{100}{\sqrt{2000}}

    could you help me with regards as to what i then do with this value of k and how i setup my equation?
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    Wait. No. ****. Sorry, ignore my last post.

    You need to integrate both sides to get an equation like t=f(A) where f(A) is some function of A. Have you done splitting the variables yet? Then you put in A and t values from part ii to get k.
 
 
 
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