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 SeeSaw.

  1. Jan 6, 2008 #1
    1. The problem statement, all variables and given/known data
    A child weighs 34 Kg is seated on a seesaw. While a child who weighs 40 kg is situated on the opposite end of the seesaw. The function B(x)= 34x / 40 gives the distance that the 40 kg child must sit from the center of the seesaw when the 34 kg child sits x meters from the center. The seesaw is 9m long find the average rate of change in distance as the lighter childs distance changes from 1.5m to 2.5meters.

    2. Relevant equations
    I used the quotient rule to find the derivative of the function. Which turns out to be 68 / 80.

    3. The attempt at a solution
    The thing is the derivative is 34/40. Which equals to 0.85.

    The prof gave us the answer which is -1.275. I havent come close to that.

    I used...

    f(x) = f(b) - f(a) / b-a

    I dont know how to tackle the average rate of change.
  2. jcsd
  3. Jan 8, 2008 #2
    you have forgotten to use the given x value.


    34*x/40 = (34 * 1.5) / 40 = 1.275
  4. Jan 8, 2008 #3

    Shooting Star

    User Avatar
    Homework Helper

    Hi stokes,

    Was the problem formulated as you have given? Are you sure something's not missing?
  5. Jan 8, 2008 #4


    User Avatar
    Homework Helper

  6. Jan 9, 2008 #5

    Shooting Star

    User Avatar
    Homework Helper

    stokes, it would be best to take help from your professor.

    And please let us know how he solved it.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Related Rates SeeSaw.
  1. Related Rates SeeSaw. (Replies: 25)

  2. Related Rates (Replies: 2)