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Math Help - Ralated rates

  1. #1
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    Ralated rates

    A stone is dropped into a deep, dark mine. A clunk is heard 7 seconds later. Estimate the depth of the shaft in feet. Ignore air resistance. Take the speed of sound as 1000 feet/second.

    Velocity of sound= 1000 ft/sec
    d = 16t^2

    can anyone help me to solve this question?
    Thank you.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by btwest69 View Post
    A stone is dropped into a deep, dark mine. A clunk is heard 7 seconds later. Estimate the depth of the shaft in feet. Ignore air resistance. Take the speed of sound as 1000 feet/second.

    Velocity of sound= 1000 ft/sec
    d = 16t^2

    can anyone help me to solve this question?
    Thank you.
    see here

    it is a very similar problem, do you understand it?
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  3. #3
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    Thank you
    I get it now, i just need to solve for s.

    <br />
\boxed{ \frac{\sqrt{s}}{4}+ \frac{s}{1000} = 7 }<br />
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by btwest69 View Post
    Thank you
    I get it now, i just need to solve for s.

    <br />
\boxed{ \frac{\sqrt{s}}{4}+ \frac{s}{1000} = 7 }<br />
    yes.

    i hope you really understood what happened and didn't just plug in the relevant numbers into TPH's equation.

    could you, for instance, tell me how he came up with the \frac {\sqrt{s}}4?
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  5. #5
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    s = 16 t^2

    t= (s/16)^1/2

     t=\frac {\sqrt{s}}4
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  6. #6
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by btwest69 View Post
    s = 16 t^2

    t= (s/16)^1/2

     t=\frac {\sqrt{s}}4
    good enough for me.

    there is an issue with signs though, but it depends on how you think about the problem. but you're good. good job
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