[Phys-L] Re: measuring the period of a pendulum

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

At 10:08 AM 11/21/2005,  Larry Smith, you wrote:
> In an introductory physics laboratory, is it better for students, when
> measuring the period of a simple pendulum, to start and stop the stopwatch
> when the bob is at the lowest point (max. speed) or at an end point (speed
> = 0)?
>
> Larry


I have rolled dissimilar balls down a ramp, timing the progression by
  heartbeats, in the Galilean manner. This gave me ample opportunity
to massage the results in ignorance of variable angular momenta
of the balls.

But I knew that more precision could be obtained by identifying an
instance of a spacetime event.    One plausible method would be to
  shine a laser pointer on the  lowest point of the pendulum's bob.

That would give me an easy opportunity to discover that holding a photo
sensor near the bob, and connecting to an oscilloscope or counter
or electronic stop watch or viewing with a videocamera
  would give more reproducible results.


Brian Whatcott    Altus OK    Eureka!
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