- No measurements are exact; there is always some degree of uncertainty. For example, 13.995m.
- The only time when we are "certain" about a measurement is when we count. For example, 31 people.
Absolute Uncertainty
- Expressed in units of measurement.
- Method 1: Make at least three measurements and calculate the average. You should disregard the measurement that is farthest apart from the rest of the other measurements before you calculate average. The absolute uncertainty is the largest difference between the average and the lowest or highest reasonable answer.
- Method 2: Determine the uncertainty of each instrument you're using. Always make the measurement to the best precision that you can. Therefore, you should estimate to fraction 0.1 of the smallest segment on the instrument scale.
On a ruler, the smallest division is 1mm. The best precision is to break this into 10 equal pieces = 0.1mm.
Relative Uncertainty = Absolute Uncertainty/ Estimated measurement
- Can be expressed as a percentage or in sig figs
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