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Homework Help: Tension of rope between 2 blocks

  1. Oct 27, 2012 #1
    Hey guys I"m new to the forum so I just wanted to say whats up? You'll be seeing me a lot more often btw. :]

    1. The problem statement, all variables and given/known data
    Rachel is pulling 2 blocks across a horizontal friction less surface with an acceleration of 1.5m/s/s. The mass of Block 1 is 4kg and Block 2 is 2kg.

    1) What is the tension in the rope between the blocks?
    2) What is the tension of the rope being pulled?

    Diagram :


    2. Relevant equations

    F=ma is all I know because I missed the lesson where my teacher went over tension, I missed class due to a religious holiday btw.

    3. The attempt at a solution

    Well because its a friction-less surface I don't have to worry about that, but all I have to work with is
    2 masses

    So only guess I have is because the blocks are being pulled horizontally the answer to part 1 might be just FofBlock2 - FofBlock1 = T1? (If you look at the diagram it makes more sense!)

    For part 2 I have no idea..
  2. jcsd
  3. Oct 27, 2012 #2


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    Staff: Mentor

    You can use F=ma to calculate the force on the left hand block. Then consider the total force on the right-hand block.
  4. Oct 27, 2012 #3
    What do you mean by consider it?
  5. Oct 27, 2012 #4


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    Write an expression for the net force on the right hand block. What value does it need to have to produce the desired acceleration?
  6. Oct 27, 2012 #5
    We already have acceleration though?

    But on the right hand block would FofBlck1= Ftotal - FofBlock2 ?

    And how do I find T2?
  7. Oct 27, 2012 #6


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    What do you mean by these quantities: FofBlck1, FofBlock2, Ftotal ?

    The tension, T1 in rope 1 is the force acting to the right on block, B1.

    The tension, T2 in rope 2 is the force acting to the left on block, B1.

    The tension, T2 in rope 2 is also equal the force acting on block, B2, but it acts to the right on B2.

    What's the net force on each block?
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