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Homework Help: Rotational Motion around a Fixed Axis

  1. Nov 11, 2006 #1
    Hi, I'm really confused about these 2 problems to the extent that I have no idea where to start.

    Any kind of suggestions and hints would be really appreciated.


    A 1090-N uniform beam is attached to a vertical wall at one end and is supported by a cable at the other end. A 1960-N crate hangs from the far end of the beam. Using the data shown in the figure, find (a) the magnitude of the tension in the wire and the magnitudes of the (b) horizontal and (c) vertical components of the force that the wall exerts on the left end of the beam.


    A block (mass = 1.4 kg) is hanging from a massless cord that is wrapped around a pulley (moment of inertia = 1.3 x 10-3 kg·m2), as the figure shows. Initially the pulley is prevented from rotating and the block is stationary. Then, the pulley is allowed to rotate as the block falls. The cord does not slip relative to the pulley as the block falls. Assume that the radius of the cord around the pulley remains constant at a value of 0.049 m during the block's descent. Find (a) the angular acceleration of the pulley and (b) the tension in the cord.

  2. jcsd
  3. Nov 11, 2006 #2


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    Homework Helper

    Regarding the first problem, do you know how to express equilibrium?
  4. Nov 11, 2006 #3

    hmm not exactly,

    I guess I'll read over the chapter again and see.
  5. Nov 11, 2006 #4


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    Homework Helper

    Do so. And if you're still unsure after that, you can use the search button with words like 'static, equilibrium', etc. to see some examples.
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