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Angular Speed of a swinging stick

  1. Oct 12, 2006 #1
    I having trouble answering this one. I already had to calculate the change in potential energy but am now stuck.

    A stick with a mass of 0.168 and a length of 1.00 is pivoted about one end so it can rotate without friction about a horizontal axis. The meter stick is held in a horizontal position and released.
    1) As it swings through the vertical, calculate the angular speed of the stick.

    I thought I could answer this by using the equation:
    (ω_f)^2 = (ω_i)^2 + 2α Δθ
    This does not work and I don't know where to go from here.

    2) As it swings through the vertical, calculate the linear speed of the end of the stick opposite the axis.
  2. jcsd
  3. Oct 12, 2006 #2
    Have you drawn a picture yet, or are you just guessing that the equation will work? Make a free body diagram, and examine all the forces throughout the equation. This is really just a pendulum. How long do you think it would take the pendulum to go to the other side, and then back again? What do you suppose its period is?
  4. Oct 12, 2006 #3

    Doc Al

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    Staff: Mentor

    That equation assumes constant acceleration, which is not the case here. Hint: Consider conservation of energy.
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