1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Oscillation of rope problem

  1. Apr 26, 2005 #1
    A 55.0 kg circus performer oscillates up and down at the end of a long elastic rope at a rate of once every 8.40 s. The elastic rope obeys Hooke's Law. By how much is the rope extended beyond its unloaded lenght when the performer hangs at rest?

    I drew a free body diagram and summed up the forced to get:
    [tex]F_{t} - mg= 0[/tex]
    Since [tex] F_{t}= -kx [/tex] , I substituted it in.
    Using the equation [tex] t= 2\pi\sqrt{m/k} [/tex], I solved for k and got .316. I plugged this into the equation and got x=1705 m, which isn't right... can someone tell me what I'm doing wrong?
  2. jcsd
  3. Apr 26, 2005 #2

    Doc Al

    User Avatar

    Staff: Mentor

    That equation is OK, but your answer for k is not. Redo it.
  4. Apr 26, 2005 #3


    User Avatar
    Science Advisor
    Homework Helper

    Do an estimate to see if your k value is reasonable

    [tex] T/2\pi = \sqrt{m/k} [/tex]

    must be about 8.4/6 which is about 1.4

    How must the numerical value of k compare to the numerical value of m?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook