1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Related Rates

  1. Mar 8, 2009 #1
    Sand is falling into a cone whose height is always 1/2 the diameter of the base. If the sand is falling at a rate of 1/2 cubic meters per min. How fast is the height increasin when the pile is 3 meters high?

    so far i've drawn my diagram and got this far.

    Given:
    h = 1/2 the base
    dv/dt = +1/2m3/min

    Needs:
    dh/dt

    the equation i was going to use is
    V = 1/12pih3

    then i get

    dv/dt = (1/2pi)(3h2)dh/dt

    i dont know how to get the h?
    any help?
     
  2. jcsd
  3. Mar 8, 2009 #2

    gabbagabbahey

    User Avatar
    Homework Helper
    Gold Member

    You're asked to find dh/dt when the height is 3 meters....so h=3:wink:

    But there is a problem with your starting equation V = (1/12)pih3....If the height is always half the diameter, then r=4h not h/4
     
  4. Mar 8, 2009 #3
    ok, that was stupid of me,
    i dont even know why i was having trouble with that now >.<
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Related Rates
  1. Related rates formula (Replies: 3)

Loading...