Explain how you decided if the two measurements agree or not. If they do not agree, identify a relevant assumption from the experiment that could cause the disagreement.
- The results from the two methods are far away from each other. They are also beyond the limits of uncertainty f any one. friction between the table and the top mass is ignored.
Simple Method for Estimating Uncertainty
• Repeat the measurement 3 or 4 times.
• The average value of the measurements is the best estimate of the measured quantity.
• Half the difference between the smallest and the largest measurements provides an estimate of the spread of these data points.
• Divide the spread by the square root of the number of measurements to find an estimate for the uncertainty on this average.
• Report the average plus or minus the uncertainty on the average.
Example: Suppose you measure 31, 27, and 26.
• The average is (31+27+26)/3 = 28
• The spread is (31-26)/2 = 2.5
• The uncertainty is 2.5/√ = 1.44
• The best estimate of your measured quantity is 28 ± 1.44, which is equivalent to saying that it is most likely to lie somewhere in the interval between 26.56 and 29.44.
