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!

2 masses, 3 pulleys

  1. Dec 16, 2015 #1
    1. The problem statement, all variables and given/known data

    Find the acceleration of the masses
    PAAcdkT.jpg

    2. Relevant equations
    ##F=Ma##

    3. The attempt at a solution
    We know that the system is moving so for ##M_1## we have ##M_1gsin\theta## on the other hand on ##M_2## we have ##M_1gsin\theta-M_2gsin\theta##

    How can I conclude that the acceleration of ##M_2## is twice of ##M_1##?
     
  2. jcsd
  3. Dec 16, 2015 #2

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    I assume you meant the other way around.
    It follows from the assumption that the string length does not change.
     
  4. Dec 16, 2015 #3
    Sorry ##M_1## is twice the acceleration as ##M_2##.

    Yes the string length does not change
     
  5. Dec 16, 2015 #4

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Do you see how it follows from that?
     
  6. Dec 16, 2015 #5
    No I can't understand the forces map
     
  7. Dec 16, 2015 #6

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    It's not to do with the forces. Consider the lengths of the three sections of strings. They add up to a constant, and two are always the same as each other. That allows you to express two in terms of the third. Then see how they relate to the two accelerations.
     
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: 2 masses, 3 pulleys
  1. 3 mass, 3 pulley (Replies: 3)

Loading...