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Homework Help: Questions about simple pendulum

  1. Nov 2, 2004 #1
    1) A simple pendulum consist of a mass m tied to a string (considered massless) of length L. So would a baseball bat suspended from one end, swinging back and forth, make a simple pendulum?

    No, right? because the "string" in this case is not massless. Does the string that is swinging the mass always have to be massless for it to be a simple pendulum?

    2) Under what conditions does an oscillating mass tied to a string constitute a simple pendulum?

    Is it considered a simple pendulum when the mass is displaced from the suspension point?

    3) The period of the variable-g pendulum is T^2 = K(1/geff).
    Upon what variables does K depend? (Hint: The moment of inertia is involved.)

    don't know about this question :frown:
  2. jcsd
  3. Nov 3, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    These questions strike me as a bit odd.
    By usual definition, a simple pendulum is a point mass at the end of a massless "string". So, right, a baseball bat is not a "simple pendulum", but would be an example of a physical pendulum. But I'm not getting the point of the question.

    Again, I have a hard time understanding the question. What's an "oscillating mass"? Do they mean a mass swinging at the end of a string? If the string is massless, it's a simple pendulum.

    I'm guessing that they are looking for is under what conditions does this pendulum exhibit simple harmonic motion. Try answering that one.

    I don't know what a "variable-g" pendulum is. In any case, figure out (or look up) the equation for the period of a physical pendulum.
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