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Homework Help: Tension blocks

  1. Nov 26, 2009 #1
    1. The problem statement, all variables and given/known data
    1. The problem statement, all variables and given/known data
    There are three blocks on a table. They are connected by a massless cord and pulled to the right. From rigt to left, it follows: T3, block 3, T2, block 2, T1, block 1
    m1: 2.5kg
    m2: 9.5kg
    m3: 1.5kg
    mu kinetic: .051
    The pulling force is equal to T_3 = 98.0 N. What is the tension T_2?

    2. Relevant equations
    fnet = ma
    Fapp(T3) - Fk3 - Fk2 - Fk1 = ma
    T2 - Fk2 = 9.5a

    3. The attempt at a solution

    well firstly i tried finding the acceleration of the system using all the forces being applied.
    i did Tension 3 - all the friction = ma
    and acceleration comes out to be 1.336m/s^2

    then i sub this back into the 2nd block system equation.

    T2 - Fk2 = 9.5a
    and Tension2 comes out to be 60.173N.
    Is this correct? if i missed a step or did somethign wrong please correct me thanks.
  2. jcsd
  3. Nov 28, 2009 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Your method is correct, but I don't agree with the value you got for the acceleration. Can you show exactly what numbers you put in this equation and how you solved for a?

    Fapp(T3) - Fk3 - Fk2 - Fk1 = ma
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