T = mr (g-a),
where a is the acceleration of the mass. If the assumption holds that the only friction affecting the potentiometer was constant Coulomb friction, then each mass would undergo a constant acceleration.
The potentiometer measured voltage versus time for the masses as they dropped, but the measurement of interest to us was position versus time. For that reason, a ‘calibration’ was performed before we measured any data. In the calibration, the potentiometer’s initial voltage was measured. Then the string was pulled a set distance (2 inches), and the voltage was recorded. This process of pulling the string a set distance and recording the voltage continued another two times (see Appendix A for the results). To determine the relationship between voltage and position, the differences in the voltages were averaged and divided by the length. The resulting relationship was 0.9661 volts/inch.
Five different masses were used to test the assumption of constant acceleration. For each mass, the string was rolled up on the shaft, the oscilloscope was triggered, and the shaft was released. As each mass dropped, the oscilloscope collected the potentiometer’s voltage versus the time. After obtaining plots for each mass, we used the
voltage-position relationship, mentioned above, to convert the data from the form voltage versus time to the form position versus time squared.The residuals of the data determined whether the assumption of constant acceleration was valid.
Results
实验的数据，公式，图表，计算过程，用一种对读者最友好的形式展示出来。 实验的原始数据通常都是放在附录的，这里都是放处理过的数据。
如果有大量的计算，至少要列出其中一个sample calculation.
Results部分的开头最好重复一下实验目的。
如果结果很多，最好分成不同的section
example:
Results
Overall, beavers showed a preference for certain species of trees, and their preference was based on distance from the central place.
Measurements taken at the study site show that beavers avoided oaks and musclewood (Fig. 1) and show a significant food preference (x2=447.26, d.f.=9, P<.05). No avoidance or particular preference was observed for the other tree species. The mean distance of 8.42 m away from the water for not-chewed trees was significantly greater than the mean distance of
6.13 m for chewed trees (t=3.49, d.f.=268, P<.05) (Fig. 2). The tree species that were avoided were not significantly farther from the water (t=.4277, d.f.=268, P>.05) than selected trees. For the selected tree species, no significant difference in circumference was found between trees that were not chewed (mean=16.03 cm) and chewed (mean=12.80 cm)
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