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Homework Help: Finding the tension of a string with 2 blocks attached.

  1. Dec 6, 2009 #1
    1. The problem statement, all variables and given/known data
    There is a string hanging down with a 2 kg block attached, at the bottom of this block is another string attached holding another 2 kg block. This has begun to accelerate. The given time is .7 s for acceleration, and the given velocity it reaches is .35.
    I have to find the tensions of both the strings, and I am not exactly how to/what formulas to use.

    So far I have calculated the acceleration to = .5 m/s2 though.
    But I do not know how to use it.
  2. jcsd
  3. Dec 6, 2009 #2
    Calculate the acceleration using Vf = Vo + at then,

    Consider the 2 block system as a one block system, calculate the tension.

    (Hint: Newtons 2nd Law)

    Then define the 2 seperate tensions accordingly.
  4. Dec 6, 2009 #3
    First body: m*a=sum of all forces acting on it=T1-T2-mg
    Second body m*a=T2-mg

    Adding the two equations gives 2m*a=T1-2mg
    T2 can be solved directly.

    Edit: sorry Jeques, simultaneous post. I'm happy for the help and will say good night!
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