1.5. Working with Error http://www.ck12.org
FIGURE 1.14
Graph showing 2 pound offset due to
calibration error.A group of students wish to find the time of fall for a golf ball dropped from a height of 4.9 m. Students take turns
dropping the ball and recording the time. They’ve devised this procedure to avoid the systematic error introduced by
having the same person drop the ball and the same person time the fall for each trial. They make sure that at least
ten data points are collected. The data appear as follows inFigure1.15.
FIGURE 1.15
Experimental results of timing a fall of 4.9
m. The time to fall 4.9 m is theoretically
1.00 s.The resulting data was the following times: 0.92, 0.96, 1.12, 0.94, 1.07, 1.03, 1.00, 0.98, 0.91, 0.99
The average value of the data set is: 0.992 = 0.99 s.
The theoretical value (the accepted value) is 1.00 s.
It seems clear from the data that the timing device’s smallest interval of precision is 0.1 s. Therefore, the last digit of
each measurement (0.01 s) was significant but uncertain. The timing device has a precision of±0.05 s, so the final
result is within the range [0.94 - 1.04] s. This means the experiment worked quite well, since the accepted value of