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!

Help? Tension problem?

Tags:
  1. Mar 18, 2017 #1
    1. The problem statement, all variables and given/known data

    Determine the acceleration of the system and the tension in the connecting cord.

    Mass 1 = 2.8kg
    T1 = ?
    Mass 2 = 1.2kg
    T2 = ?
    mu = .2

    *My picture is kinda bad but you can see how its set up*


    2. Relevant equations

    ∑F = m*a


    3. The attempt at a solution

    I drew a FBD for Block A -->
    ∑Fx = m*a

    T1 - ƒ = m*a
    T1 = m*g*mu + m*a

    For Block B -->
    Down = positive
    T2 = mg - ma


    My question is... are the two tensions equal? Would I just set these two equations equal to each other & solve for a and than solve for T?
     

    Attached Files:

  2. jcsd
  3. Mar 18, 2017 #2

    gneill

    User Avatar

    Staff: Mentor

    Assuming that there is light, frictionless pulley where the cord makes a right angle turn then yes, the tension will be the same everywhere in the cord.
     
  4. Mar 18, 2017 #3
    So I guess m cancels?
    For a I got :
    a = 1/2(g-mu*g)
    a = 3.92 m/s/s

    Than: For block 2 (mass = 1.2kg)
    T2 = mg - ma
    T2 = 7.056 N

    For block 1 (mass = 2.8kg)
    T1 = m*g*mu + m*a
    T1 = 16.464 N

    So what tension is it?
     
  5. Mar 18, 2017 #4
    Can you explain where this equation came from?

    And if it is a frictionless pulley, then T1 and T2 should be equal, true?
     
  6. Mar 18, 2017 #5
    T1 = m*g*mu + m*a
    T2 = mg - ma
    m*g*mu + m*a = mg - ma
    g*mu + a = g - a
    2a = g - g*mu
    a = (1/2)(g - g*mu)

    I'm kinda confused?
     
  7. Mar 18, 2017 #6
    You can't cancel out the masses because they aren't all the same. Some are m1 and some are m2.
     
  8. Mar 18, 2017 #7
    Oh wow hahahah thank you
    XD
     
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: Help? Tension problem?
  1. Tension Problem Help! (Replies: 2)

Loading...