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!

Homework Help: A question about Tensions

  1. Mar 31, 2013 #1
    1. The problem statement, all variables and given/known data

    Identical K,L and M bodies with a weight of P are in equilibrium . If the tension in the rope S1 is T1 and S2 is T2, then what is the ratio T1/T2? (The picture is below)

    2. Relevant equations

    3. The attempt at a solution

    T1 equals P. But I am stuck with T2. I cannot decide whether it is 2P or 3P. Do we have to add the weight of K to T2? If we add, it will be 3P.

    Attached Files:

    Last edited by a moderator: Mar 31, 2013
  2. jcsd
  3. Mar 31, 2013 #2


    User Avatar
    Science Advisor

    S2 is the uppermost vertical string and so must support all of the weight. Its tension will be 3P.
  4. Mar 31, 2013 #3
    Then the answer is 1/3.But according to my book the answer is 1/2.
  5. Mar 31, 2013 #4
    the pulley is attached to a rigid support.T2 has a weight of 2P
  6. Mar 31, 2013 #5
    Let us call A the node above K and B the node above L. Let us assume that the angle between a horizontal line and the rope connecting A to B is 45 degrees (without this value you cannot compute a solution). Then you only have to write the equilibrium conditions at nodes A (first) and B (second).
    The ratio is 1/2.
  7. Mar 31, 2013 #6
    Many Thanks
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted