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Math Help - time derivative of a variable os inversly proportional to other variable

  1. #1
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    time derivative of a variable os inversly proportional to other variable

    Hi,
    I have the following question:

    If the time derivative of a variable (A) is inversly proportional to some other variable (B), and we want a high variation in values of (B) values for different time steps, then should (A) be varying more or less?

    Anyone, please reply. Thanks in advance
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by lalleykhan View Post
    Hi,
    I have the following question:

    If the time derivative of a variable (A) is inversly proportional to some other variable (B), and we want a high variation in values of (B) values for different time steps, then should (A) be varying more or less?

    Anyone, please reply. Thanks in advance
    1. If you want help you should put more effort into making your question clear.

    2. Lets assume you mean you have:

    B(t)=\frac{k}{A(t)}

    Then:

    B'(t)=-\frac{kA'(t)}{(A(t))^2}

    Now what were you asking again?

    CB
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  3. #3
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    I would interpret "the time derivative of a variable (A) is inversly proportional to some other variable (B)" as meaning \frac{dA}{dt}= \frac{k}{B}. But, then, that does NOT give any condition on the derivative of B so I suspect CaptainBlack's interpretation is the correct one.
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