to 1.8m before adding the two quantities together. When multiplying or dividing the
result must match the original quantity with the least amount of sig figs. For example
when multiplying 25.9m and 3.1m the result would be 80.29m without rounding to the
correct amount of significant figures, but after rounding to the original quantity with the
least amount of significant figures the correct answer would just be 80m. Due to the
many sets of data that is collected that could vary in uncontrollable ways, then the best
way to look at the data is through the mean value of all measurements (this statement is
not necessarily true for all sets of data). According to the theory of measurement the
measurements should form a “normal distribution”. Even though a “normal distribution”
would seem accurate there is still some uncertainty. The amount of uncertainty will be
such that the probability of any new measurement falling in the interval from the mean
minus the uncertainty will be about 67%. This definition of uncertainty is called the
“standard deviation of the mean” and will be denoted by
σ.
σ=sqrt(Σ
n
i=1
(x
i
x)
2
/N).
The lab had the students measure the period of the pendulum with
a timer 40 times. The students set up a wooden block with a string and ball attached to a
stand. One student recorded the time in seconds it took the pendulum to make a full
cycle. The other student has a stopwatch and makes the pendulum do a full cycle while
starting and stopping the stopwatch when letting go of the ball and the ball returning to
the student’s hands. The data should be recorded to 0.01s. Student must try to keep the
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 Fall '11
 BrunoBauer
 Physics, Normal Distribution, Standard Deviation, Tom Rushton

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