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!

Pulleys and Springs: Really stupid question

  1. Apr 17, 2009 #1
    So I am trying to follow along this example in the text to find keq of the system.

    I can follow everything up until the point that they say: "It follows that x=2(x1+x2)

    where:

    x = displacement of mass
    x1 =displacement of Pulley1cm
    x2 =displacement of Pulley2cm

    I am not seeing it. I am also very tired. So please help me and then slap me :smile:

    Picture6-3.png
     
  2. jcsd
  3. Apr 18, 2009 #2

    rl.bhat

    User Avatar
    Homework Helper

    For the time being, suppose k2 is not operating. When the pulley1 moves up through x1, what is the distance moved by the mass ?
     
  4. Apr 18, 2009 #3
    Yeah. I don't see it. How ca I relate anything to x?

    Like rl.bhat says: If k2 was not operating, I know that 2W=k1*x1 ... but I
    don't see how that helps?
     
  5. Apr 18, 2009 #4
  6. Apr 18, 2009 #5

    rl.bhat

    User Avatar
    Homework Helper

    Just compare the movement of the pulley and release of the rope at mass end.
    When the pulley1 moves through x1, mass moves through y1 distance ,then y1 = 2x1. Similarly for pulley 2, y2 = 2x2. So the distance moved by the mass y1 + y2 = x = 2(x1 + x2)
     
  7. Apr 18, 2009 #6
    Okay. I mean, I believe you. I just don't see it.
     
  8. Apr 18, 2009 #7

    rl.bhat

    User Avatar
    Homework Helper

    When p1 moves up through x1, on both side of the pulley x1 rope is released. That adds up to 2x1.
     
  9. Apr 18, 2009 #8
    Ahh. I think I see it now. Thanks for your patience!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Pulleys and Springs: Really stupid question
  1. Spring & pulley (Replies: 12)

  2. Stupid question (Replies: 2)

  3. Pulley on a Spring (Replies: 6)

  4. Pulleys and springs (Replies: 22)

Loading...