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Homework Help: Horizontal Atwood Machine

  1. Apr 17, 2017 #1


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    We had a lab using an Atwood Machine with block A being on the surface and block B as the hanging object with different masses each round. Rolling resistance was present. Question 1 asked whether or not the tension in the string was less than, greater than or equal to the magnitude of the gravitation force acting on the hanging mass (as the objects are accelerating). Question 2 asked, while the carts were accelerating, was the acceleration of the hanging mass less than, greater than or equal to the standard gravitational acceleration. After applying newtons law, I calculated that for both q1 and q2 the values were less than.

    Q3 asks how would your answers to the first two questions change if the rolling resistance of the cart could be reduced to zero? Explain why this must be. I calculated this by doing Fnet(y)=-ma(y) and my answers were slightly smaller but insignificant. I am not sure why this is.
  2. jcsd
  3. Apr 17, 2017 #2


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    Staff: Mentor

    Welcome to the PF.

    First, please use the Homework Help Template that you are provided when starting a new schoolwork thread here. I'll paste in a copy below.

    Also, it's very hard to visualize the setups you are asking about. Can you post sketches or pictures of the situations? Also, can you draw Free Body Diagrams (FBDs) for all of the pieces involved? Thanks.

    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  4. Apr 17, 2017 #3


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    There was a track on the table and a cart was placed on it. There was a pulley attached to the cart and hanging at the edge of the table was a "hanging mass". On block A there was rolling resistance/friction between the block and the table as well as Fg and tension from the pulley/string. On block B there was Fg as well as tension from the rope. (This is my first time posting so I'm not sure how to ad in a drawing).
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