Re: Systematic vs. Random

[John Howell <jhowell@EARLHAM.EDU>]

Two specific examples of what Jack Uretsky  refers to as reassessing
the theory:

One possible systematic error would be that the angular amplitudes of
the pendulums were different, with longer pendulums having
systematically smaller amplitudes.  E.g., if the initial displacement
of the pendulum is always 10 cm, that would correspond to a higher
angular amplitude for shorter values of L.

Another source of error could be that the pendulum you used need to
be treated as physical pendulum, rather than as a simple pendulum.

I have no way of knowing whether either of these is likely to result
in an error of 4%.

> During a post lab discussion yesterday students were presenting
> the results of the standard pendulum lab (l vs. T).
>
> A student asserted that because the test plot of T^2 vs. l by another
> team resulted in a y-intercept that was about 4% of the maximum T^2
> value then there was probably a "systematic error".  My first reaction
> (while the students discussed this) was that this was not true.  The bell
> rang. All left.  I will see them again last period today.
>
> I would like to get the general thoughts some on this list might have
> regarding the validity of making the "systematic error" assertion based on
> y-intercept value (combined with 9 well fitted data points).
>
> Thanks
>
> Tim