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Finding tension and force in a cord

  1. Nov 15, 2009 #1
    1. The problem statement, all variables and given/known data

    Hey there,

    Here is the problem: A weight of 2 kg is suspended by a single cord. An horizontal force keeps the cord at 37 degrees from the vertical. Find (a) the force, (b) the tension in the cord.

    Relevent equations are Weight = mass x acceleration, I use 9,81 m/seconds squared for the gravitational acceleration.

    Here is my attempt at a solution:

    I started by drawing a diagram of the problem. Then I tried to set my equations:

    The sum of my forces in x = 0 N = -cos(90-37)T
    First of all I am unsure of this one, this doesn't really make sense because my weight isn't moving horizontally, while if I base myself on this equation it should be in movement.

    The sum of my forces in y = 0 N= -Weight + sin(90-37)T

    Basically this is what I thought but I soon realized that these two equations could not work, maybe the second one but the first one definitely not. Then, I couldn't figure out what I was missing. Can you guys help me out, and show me the methodology to do this problem.
    Thanks a lot everybody!
     
  2. jcsd
  3. Nov 16, 2009 #2
    Solve for T from the sum of forces in Y equation, since the only unknown is T.
    Now substitute T into the "x Sum" equation to solve for the horizontal force.

    The x direction equation should be:
    0 = Fh - Tsin 37
    That equation does not imply movement, it is that the horizontal component of the rope tension is balanced by the restraining force, Fh
     
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