Re: Periodic motion vs. oscillation

["Carl E. Mungan" <mungan@USNA.EDU>]

Michael Edmiston wrote:

> One of the lab experiments my students do is show that the simple
> pendulum, when undergoing oscillation, has a period that is amplitude
> dependent, which is one aspect that results from the fact that the
> simple pendulum is not "simple harmonic motion" (i.e. the restoring
> force is not linear).  One of the difficult aspects of the experiment
> (which requires very accurate timing of the period) is releasing the
> pendulum so it is an oscillatory pendulum rather than a conical
> pendulum.  Using photogate timers it is a piece of cake to measure the
> period with sufficient accuracy to demonstrate the amplitude dependence.
> However, keeping the oscillation from becoming a conical pendulum
> requires a better release than many students can obtain.

Why don't you use a double-hung pendulum, that is a string tied to a
horizontal bar at two ends that loops through a hole in the mass so
that the string makes a V-shape:

  ===================
  \                 /
   \               /
    \             /
     \           /
      \         /
       \       /
        \     /
         \   /
          \ /
           O
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5040
mailto:mungan@usna.edu       http://usna.edu/Users/physics/mungan/