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Homework Help: Dynamics - Newtons 2nd law.

  1. Feb 3, 2012 #1
    1. The problem statement, all variables and given/known data

    I attached the photo of the question that has everything.

    2. Relevant equations

    [itex] F=ma [/itex]

    3. The attempt at a solution

    So I found the total mass of the system 50+35 = 85. Since we are given the force in the x-direction I used [itex] \frac{70}{85} = a = .8235 [/itex]. The weight of the cylinder is 50*g = 490 N, and weight of the cart is 35*g = 343 N. But I don't know where to go from there. I know that the reaction at A will be larger than at B because the "pulling" force will cause the cylinder to push more on the left side of the cart.. But I don't know how to relate anything to get useful equations.

    Attached Files:

  2. jcsd
  3. Feb 3, 2012 #2


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    Your acceleration calc in the x directon is correct. The cylinder must also move at that same acceleration in the x direction. What is the cylinder's acceleration in the y direction? You must draw a free body diagram of the cylinder and identify the forces acting on the cylinder in the x and y directions. In what direction do the normal forces act? Then use newton's laws in the x and y direction.
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