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!

Dependent motion problem with ropes

  1. Mar 1, 2012 #1
    1. The problem statement, all variables and given/known data
    I attached the problem with my attempt.

    The problem I have is that I have two unknowns. I think my set up is wrong. Does anyone know where to put the datum/set up this question?

    Thanks!
     

    Attached Files:

  2. jcsd
  3. Mar 1, 2012 #2

    gneill

    User Avatar

    Staff: Mentor

    What are your two unknowns? Remember, you're looking for dependencies between certain length changes.
     
  4. Mar 1, 2012 #3
    I know it's A and C but I don't know how to get rid of B :S
     
  5. Mar 1, 2012 #4

    gneill

    User Avatar

    Staff: Mentor

    Here's your drawing with the distances labeled.

    attachment.php?attachmentid=44622&stc=1&d=1330662443.gif

    Your equation is:

    L = SA - SB + 2SC

    What you're looking for is the rate of change of SA with respect to a rate of change of SC. So rearrange your formula to have SA on the left and the rest on the right. Now, are you familiar with calculus (derivatives)?
     

    Attached Files:

  6. Mar 1, 2012 #5
    Oh... I see, so if you take the derivative Sb and L are eliminated since they are constant?
     
  7. Mar 1, 2012 #6

    gneill

    User Avatar

    Staff: Mentor

    Yup.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Dependent motion problem with ropes
  1. Dependent motion (Replies: 1)

  2. Rope problem (Replies: 1)

  3. Rope problem (Replies: 1)

Loading...