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!

Pendulum forces component form

  1. Feb 18, 2015 #1
    1. The problem statement, all variables and given/known data
    Hi, I need help in solving question c) (a pendulum) The required data, problem and relevant equation is in the picture

    3. The attempt at a solution
    I am not sure how to solve it but here are my thoughts:
    since mg is working at j
    y(t)j= mg
    does that mean K(r-L0) x(t) direction?
    I am not sure how to start/think to solve this problem so any tips will be helpfull, thanks!

    Attached Files:

  2. jcsd
  3. Feb 18, 2015 #2
    Look at the vector attached to the second term. It is not in the i / x direction but rather in the r direction. It acts directed from the radius of the pendulum. What law describes this force?

    Also, think why do we divide the r vector by its magnitude?
  4. Feb 18, 2015 #3
    Is it Hookes law?
    I assume we divide r vector by its magnitude to determine the direction of the force
  5. Feb 18, 2015 #4


    User Avatar
    Homework Helper

    the rope stretches along its length like a spring. all c) asks you to do is split the diagonal Force into (x,y) components.
  6. Feb 18, 2015 #5
    Is mg=y component correct or is it wrong?
    And what force is working in the x direction? Or did I misunderstand what the task is asking for?
  7. Feb 18, 2015 #6


    User Avatar
    Homework Helper

    mg is entirely vertical ... but most folks treat "up" as positive.
    That is not the ONLY vertical Force contribution, however. The diagonal (spring) Force has x-component and y-component.
  8. Feb 19, 2015 #7
    So K(r-L0) works both in x and y direction? Am I then supposed to split the force and find which force works in x and y direction?
  9. Feb 19, 2015 #8


    User Avatar
    Homework Helper

    the wording in part c) could not be more explicit.
  10. Feb 19, 2015 #9
    r(t)=(K*r)i-K*L0j would this be correct?
  11. Feb 22, 2015 #10
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Pendulum forces component form
  1. Component form (Replies: 8)

  2. Component form (Replies: 4)