INTRODUCTION TO MEASUREMENT, THE METRIC SYSTEM, SCIENTIFIC NOTATION, and DIMENSIONAL ANALYSIS
UNITS OF MEASURE ARE IMPORTANT
UNITS OF MEASUREMENT
Example
METRIC SYSTEM • Metric system (Le Systeme International d’ Unites) AKA “S. I. ”– common units of measurement for everyone (else) • Based on multiples or divisions of base unit 10 (remember the Dewey decimal system? ) • Common metric units of measure for: Length Mass Volume Time Energy meter gram Liter second Joule
Metric Prefixes Meter Liter gram cro mi lli mi ci de nt Base unit 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 i 100 ce ka De lo 105 104 103 102 101 Ki M eg a 106
Measurement • All measurements have some degree of error associated with them – we like to have high accuracy and high precision • Accuracy: Being able • Low accuracy / High precision • High accuracy / Low precision • Precision: Being able • Low accuracy / Low to come up with the precision same value repeatedly • High accuracy / High precision to come up with the “correct” or “accepted” value
Reading measurements • Always report measurements to one more decimal place than you are able to measure with the given scale I. e. you estimate the last digit • Always include the unit used to make the measurement – otherwise, your number is meaningless!! (ml, g, cm etc. ) ruler Graduated cylinder
Measurement • Accuracy: Being able to come up with the “correct” or “accepted” value Precision: Being able to come up with the same value repeatedly Low accuracy / High precision High accuracy / Low precision Low accuracy / Low precision High accuracy / High precision
METRICS AND MEASUREMENT Described in terms of ACCURACY and PRECISION
METRICS AND MEASUREMENT 1. Measurements can be: • QUANTITATIVE: numerically represented and measured • Ex. : length of hair = 4. 7 cm, volume of soda = 356 m. L • QUALITATIVE: descriptive • Ex. : color of hair = brown, taste of soda = sweet