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Homework Help: Newton's Law of Motion

  1. Feb 5, 2008 #1
    hello i'm having trouble with this question.

    Hanging Chandelier

    A chandelier with mass m is attached to the ceiling of a large concert hall by two cables. Because the ceiling is covered with intricate architectural decorations (not indicated in the figure, which uses a humbler depiction), the workers who hung the chandelier couldn't attach the cables to the ceiling directly above the chandelier. Instead, they attached the cables to the ceiling near the walls. Cable 1 has tension T_1 and makes an angle of theta_1 with the ceiling. Cable 2 has tension T_2 and makes an angle of theta_2 with the ceiling.


    Find an expression for T_1, the tension in cable 1, that does not depend on T_2.
    Express your answer in terms of some or all of the variables m, theta_1, and theta_2, as well as the magnitude of the acceleration due to gravity g.

  2. jcsd
  3. Feb 6, 2008 #2
    Second question: A dock worker applies a constant horizontal force of 80.0 N to a block of ice on a smooth horizontal floor. The frictional force is negligible. The block starts from rest and moves 12.0 m in the first 6.00 s.

    What is the mass of the block of ice?


    please help me
  4. Feb 6, 2008 #3
    For your first question, draw the vertical line from the top of the chandelier to the ceiling. You know that the hypotenuses of the two right triangles formed are T1 and T2. Analyze the horizontal and vertical forces on the chandelier separately--you can find their values (or at least their values in terms of the given variables) through trigonometry.

    For your second question, remember that constant force means constant acceleration in the absence of friction, because F = ma, and mass is constant. You need to find the mass, but you should be able to find acceleration with the information given (look at your kinematic equations).
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