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Homework Help: Pulling Two Blocks W/ friction

  1. Dec 22, 2009 #1
    1. The problem statement, all variables and given/known data
    Two blocks of mass m1=80 kg and m2=100 kg and attached by a string, another sting comes off of mass m1 and is pulled horizontally (kinda looks like this) (T1 & T2 are tensions)
    m2--T2--m1--T1--> there is a coefficient of friction u=.14 for both blocks, what is the tension in both strings while the system accelerates at 2 m/s^2?


    2. Relevant equations
    Fnet=ma
    Ff=u(N)

    3. The attempt at a solution
    Ok so for m1 horizontal forces are T1 to the right, T2 to the left and friction.
    T2=(100)(9.8)(.14)=137.2 N Friction for m1=(80)(9.8)(.14)=109.8
    So T1-T2-Ff = m1*a therefore T1=(80)(2)+(109.8)+137.2= 407 N
    Is this Correct??
    Thanks!
     
  2. jcsd
  3. Dec 22, 2009 #2
    First consider the 2 block system as a 1 block system (combine their masses) then you can solve T1. Once you have this you can distribute T2 appropriately.
     
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