Results 1 to 2 of 2

Math Help - Rate of Change: Ladder Problem

  1. #1
    discreetthinker
    Guest

    Rate of Change: Ladder Problem

    I hope I get a response today...haha. Anyways, if anyone could help me figure this problem out. It'll be greattt...


    A math teacher is on top of a 20 foot ladder leaning against a wall when the bottom starts to slip away from the wall. The bottom of the ladder is moving away from the wall at 3 feet per second. How fast is the math teacher approaching the ground when they are 12 feet from the ground?
    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
    These ladder slipping problems are among the most over-used with regards to related rates.

    We know y=12, dx/dt=3, and can easily find x.

    If the top of the ladder is 12 feet off the ground, then the base is x=\sqrt{20^{2}-12^{2}}=16 feet from the wall.

    x^{2}+y^{2}=20

    differentiate wrt time:

    2x\frac{dx}{dt}+2y\frac{dy}{dt}=0

    Now, enter in your knowns and solve for dy/dt.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: April 12th 2011, 09:51 AM
  2. Related Rate-Ladder against the wall
    Posted in the Calculus Forum
    Replies: 38
    Last Post: November 6th 2010, 03:32 AM
  3. Rate of Change Problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: June 19th 2010, 08:35 AM
  4. Rate of Change problem
    Posted in the Calculus Forum
    Replies: 5
    Last Post: October 5th 2009, 05:04 PM
  5. Rates of Change of a 15ft ladder
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 21st 2009, 05:37 PM

/mathhelpforum @mathhelpforum