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Re: [Phys-L] pseudo-pundits +- systematic error



My guess would be that the fine folks who built your school were using 30 inch tiles.


(Don't kid yourself about any imagined inroads the metric system might eventually make here in the good ol' US of A.)



On Nov 8, 2012, at 9:08 PM, Jeff Bigler wrote:

I measured one tile to get a sense of what kinds of numbers I should
expect them to get. It was very close to exactly 75 cm, so I decided
that each tile was probably manufactured to be exactly 75 cm (or as
nearly exact as manufacturing tolerances allow), and used that number
for my calculations.

When my students obtained their data by measuring multiple tiles, it
turned out that the dimensions of the tiles varied by about +/- 2 cm.
Evidently, the expansion joints were measured and hand cut after the
floor was laid, and I happened to choose one that was exactly a
convenient round number.

Because it turned out that we had a distribution of tiles centered
around 75.5 cm, the length of the corridor outside my room as measured
with the tiles came out to approximately 36 m +/- 1 m.

--
Jeff Bigler
Lynn English HS; Lynn, MA, USA