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Homework Help: Net force, tension, acceleration, and magnitude

  1. Sep 29, 2012 #1
    1. The problem statement, all variables and given/known data
    Two blocks, of masses m1 = 10kg and m2 = 5kg respectively are connected by a massless unstretchable string and are pulled by an applied force Fa, up a frictionless incline which makes an angle of θ=30° with the horizontal. The tension in the string which connects the two blocks is T = 100N. In the figure, note carefully that the m1 = 10kg block is lower on the incline.

    Note: This question is in order to study for an upcoming exam. I've posted the answers to each question as well. I'm not sure on this one question how to do it, and would like an explanation. Would greatly help me with studying for my exam coming up!

    1.) What is the component, parallel to the incline, of the net force on the block of mass m1 = 10kg? 51N

    2.) What is the acceleration of the block of mass m1=10kg? 5.1m/s^2

    3.) What is the component, parallel to the incline, of the net force on the block of mass m2=5kg? 25.5N

    4.) What is the magnitude of the applied force Fa? 150N

    3. The attempt at a solution
    Originally I created a free-body diagram for both the masses. Afterwards I got the following:

    1.) T = m1gω
    100N = 10kg(9.8)ω
    1.02(50)N = ω

    Note: I know that this is wrong, and I'll be editing this throughout the day as I work on this question trying to figure out how to do this. Any help would be appreciated!
  2. jcsd
  3. Sep 29, 2012 #2


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    Gold Member

    I don't know what ω is supposed to represent. In order for us to better assist, please indicate what yoour FBD attempts were. Apply Newton 2 along the incline to the FBD, after identifying all forces acting parallel to the incline , including the component of the weight acting parallel to the incline.
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