1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Pendulum Oscillations Problem

  1. Dec 14, 2007 #1
    [SOLVED] Pendulum Oscillations Problem

    A very light rigid rod with a length of 0.500 m extends straight out from one end of a meter stick. The stick is suspended from a pivot at the far end of the rod and is set into oscillation.
    (a) Determine the period of oscillation. (Hint: Use the parallel-axis theorem)
    (b) By what percentage does the period differ from the period of a simple pendulum 1.00 m long?

    I tried solving for period by using t=2(pi) sqrt(L/g) but that didn't work. It says to use the parallel axis theorum but I don't know what to do once I find I. Also, I don't think I can solve the second part until I get the first period, but once I do that would it just be T=2(pi) sqrt(L/g) for the period of the pendulum with 1m length?
  2. jcsd
  3. Dec 14, 2007 #2

    Shooting Star

    User Avatar
    Homework Helper

    I think that the mass of the meter stick has to be given. Check for that.

    Basically, you have to treat the light rod and meter scale as a compound pendulum. You have to find the MI of the rod+scale using parallel axis theorem. If you know the MI of the scale about one end, then you can find the MI about the pivot.

    Read up a bit on compound pendulum or Kater's pendulum.
  4. Dec 14, 2007 #3
    It definitely doesn't give the mass, although I know you need it to find MOI. Does anyone know a way around this?
  5. Dec 15, 2007 #4
    Never mind. I figured it out. Just put I into T=2(pi) sqrt(I/mgd) and the mass cancels out.
  6. Dec 15, 2007 #5

    Shooting Star

    User Avatar
    Homework Helper

    Good for you!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook