MEASUREMENTS AND CALCULATIONS CHAPTER 2

1. MEASUREMENTS AND CALCULATIONS CHAPTER 2

2. SCIENTIFIC METHOD • OBSERVATIONS/PROBLEM • HYPOTHESIS • EXPERIMENTS • DATA • CONCLUSION-THEORIZING • REPEAT

3. UNITS OF MEASURE MEASUREMENTS ARE QUANTITATIVE INFORMATION. A QUANTITY IS SOMETHING THAT HAS MAGNATUDE, SIZE, OR AMOUNT. QUANTITY AND MEASUREMENT ARE NOT THE SAME THING.

4. SI MEASUREMENT • Le Syst`eme International d’ Unit`es: universal measurement accepted by scientists worldwide. • It contains 7 base units with others derived from this original 7. • These units are based on the metric system.

5. 7 BASE UNITS • METER • KILOGRAM • SECOND • KELVIN • MOLE • AMPERE • CANDELA

6. MASS LENGTH • MEASURED IN KILOGRAMS • IS NOT WEIGHT: A MEASURE OF THE PULL GRAVITY. • TO CALCULATE WEIGHT YOU TAKE YOUR POUND MASS, DIVIDE BY 2.2, THEN MULTIPLY BY 9.8 • MEASURED IN METERS • OTHER UNITS INCLUDE KILOMETER AND CENTIMETER

7. DERIVED UNITS AREA – LENGTH X WIDTH METERS SQUARED VOLUME – LXWXH METERS CUBED DENSITY MASS/VOLUME KG/METERS CUBED MOLAR MASS – MASS/MOLE KG/MOLE

8. CONVERSION FACTORS • THIS IS A RATIO DERIVED FROM THE EQUALITY BETWEEN 2 DIFFERENT UNITS THAT CAN BE USED TO CONVERT FROM ONE UNIT TO ANOTHER. • EXAMPLE • 1 HOUR = 60 MINUTES • CONVERSION FACTORS 1 HOUR OR 60 MINS 60 MINS 1 HOUR

9. HOW TO USE CONVERSION FACTORS TO CONVERT UNITS • CONVERT 123 MINS TO HOURS • 1 HOUR = 60 MINS SO OUR FACTORS ARE1 HOUR OR 60 MINS • 60 MINS 1 HOUR • DECIDE WHICH FACTOR TO USE BY THE UNIT YOU ARE CONVERTING. WE ARE CONVERTING TO HOURS SO THAT UNIT MUST BE ON THE TOP OF THE FRACTION. SO THE EQUATION LOOKS LIKE THIS: • 123MINS X 1HOUR • 60 MINS IN THIS PROBLEM, THE MINUTES UNIT WILL DIVIDE OUT, LEAVING THE HOUR UNIT. PERFORMING THE MATH CALCULATIONS, THE ANSWER TO THE PROBLEM WILL THEN BE 2.05HOURS