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!

Super dumb question about pulleys

  1. May 14, 2013 #1
    I know in a double pulley system, the rope moves twice the distance of the load. What about a system such as this? Would the stretch distance of the spring be twice the moved distance of the load?


    I'm having trouble visualizing these things.

  2. jcsd
  3. May 14, 2013 #2


    User Avatar

    Staff: Mentor

    Draw two pictures, one in which the spring is replaced with a length of chain one meter long and another in which the spring is replaced with a length of chain two meters long. Keep the length of the rope the same in the two pictures.

    Compare them... You'll see the answer to your question pretty quickly, and forever after be better at visualizing these things.
  4. May 14, 2013 #3
    Thanks. I think I see it now. Half of the "rope" (spring) length increase must be "used" to increase the length of the rope on the other side of the pulley. This other half of the length increase is not used to displace the system towards the bottom.

    It follows that the load would indeed only see a y = <LengthIncrease>/2 movement towards the bottom. Sorry about the vocabulary used, I'm not a native english speaker.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook