Results 1 to 2 of 2

Math Help - rate question

  1. #1
    Newbie
    Joined
    Nov 2006
    Posts
    18

    rate question

    I haven't seemed to get rate problems down yet. Can anyone help me with this one?

    water is poured into a conical funnel at a rate of 1cm"3 per second. The radius of the top of the funnel is 10cm and the height of the funnel is 20cm. Find the rate at which the water level is rising when it is 5cm from the top of the funnel.

    FYI (The formula for the volume of a cone is V=1/3 Pir"2h)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    Use similar triangles to eliminate a variable.

    \frac{r}{h}=\frac{10}{20}

    r=\frac{1}{2}h

    Sub into your volume formula and differentiate with respect to time.

    V=\frac{1}{3}{\pi}(\frac{1}{2}h)^{2}h=\frac{1}{3}{  \pi}\frac{h^{3}}{4}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: July 17th 2011, 04:49 PM
  2. rate question
    Posted in the Calculus Forum
    Replies: 2
    Last Post: November 7th 2009, 01:52 AM
  3. Rate Question
    Posted in the Calculus Forum
    Replies: 2
    Last Post: April 8th 2009, 09:03 AM
  4. rate question
    Posted in the Calculus Forum
    Replies: 6
    Last Post: November 17th 2008, 05:25 PM
  5. Rate Question
    Posted in the Algebra Forum
    Replies: 2
    Last Post: December 18th 2006, 06:14 PM

Search Tags


/mathhelpforum @mathhelpforum