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Math Help - Related rates of change.

  1. #1
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    Related rates of change.

    A cylindrical container of fixed length 90 cm is being pressure tested, and the radious id increasing at a constant rate of .01 cm/min. WHen the redious is 25 cm, find the rate of the change of:

    (a) the total surface area
    (b) the Volume
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  2. #2
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    What is the total surface area of the cylinder?

    what is the volume of the cylinder?
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  3. #3
    Member mfetch22's Avatar
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    Quote Originally Posted by delicate_tears View Post
    A cylindrical container of fixed length 90 cm is being pressure tested, and the radious id increasing at a constant rate of .01 cm/min. WHen the redious is 25 cm, find the rate of the change of:

    (a) the total surface area
    (b) the Volume
    So we have:

    V = (90)(\pi)(r^2)

    and

    SA = 2\pi r^2+2\pi r (90)

    For volume we have:

    \frac{dV}{dt} = (180)(\pi)(r)\frac{dr}{dt}

    At the values you gave we have:

    \frac{dV}{dt} = (180)(\pi)(25)(0.01)

    Thats the rate of change of the volume, can you figure it out the same way for surface area?
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