1. Chapter 1 Part 2 Precision, accuracy And significant figures
Measurement
Chapter 1
Part 2
Precision, accuracy
And significant figures

2. Precision
Precision is a measure of how well an instrument can measure if used correctly under good conditions. Examples: A car Odometer is precise to the nearest tenth of a mile. A meter stick is precise to the nearest half millimeter

3. Accuracy
Accuracy is a measure of how well a person using an instrument makes a specific measure.
Accuracy is limited by:
the precision of the instrument,
the conditions under which the measure is made
The person, his/her actions & perceptions

4. Accuracy and Significant Figures
The Convention of “Significant Figures” allows us to express the level of accuracy honestly. A measure written 4.4 m is accurate to the nearest decimeter (1/10th a meter). That is it might really be 4.41 m or 4.38 m but it is not 4.48 m or 4.5 m If you write 4.40m you are claiming that your more accurate… To the nearest centimeter!

5. Rules for Significant Figures
Non Zero numbers are always significant
Zeros between nonzero numbers are always significant
Final Zeroes to the right of the decimal are always significant
Place holder zeros are not significant…to eliminate them use scientific notation
Counting numbers and defined constants have an infinite number of significant figures

6. Calculations and Sig-fig
Calculations can make it seem that our answers are more (or less) accurate than they really are. Thus we have rules for calculating with sig-fig. Addition/Subtraction Round your answer to the last digit of your least accurate measure Multiplcation/Division Round your answer to the least number of sig-figs in your measures (Copy Examples)