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!

Unequal Accelerations in Double Atwood Machine

  1. Oct 11, 2011 #1
    I have a simple question about the Double Atwood machine.


    220px-DoubleAtwood.jpg

    I am able to follow the solution but one thing makes no sense to me. The accelerations for block A and block B are:

    a6bf5b8c63c161a91d457195a827344a.png

    431f4b7dd585fb56b793ab9272923c01.png

    Why aren't these equal? If they aren't, doesn't that mean the rope stretches? Or is this just an effect of assuming a massless rope?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 11, 2011 #2
    In the few minutes since posting this, I have realized my mistake.

    a_b and a_a are not equal because that pulley is attached to a second pulley. When that pulley A and B are attached to moves up and down, it will add a term to both a_b and a_a, making them unequal.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Unequal Accelerations in Double Atwood Machine
  1. Double Atwood Machine (Replies: 14)

  2. Double atwood machine (Replies: 3)

  3. Double Atwood machine (Replies: 5)

Loading...