# 1 Measurements. 2 Nature of Measurement Measurement - quantitative observation consisting of 2 parts Part 1 - number Part 2 - scale (unit) Part 2 - scale.

## Presentation on theme: "1 Measurements. 2 Nature of Measurement Measurement - quantitative observation consisting of 2 parts Part 1 - number Part 2 - scale (unit) Part 2 - scale."— Presentation transcript:

1 Measurements

2 Nature of Measurement Measurement - quantitative observation consisting of 2 parts Part 1 - number Part 2 - scale (unit) Part 2 - scale (unit)Examples: 20 grams 6.63    Joule seconds

3 International System (le Système International) Based on metric system and units derived from metric system.

4 The Fundamental SI Units

5 Dimensional Analysis or The Unit Factor Method Proper use of “unit factors” leads to proper units in your answer. Have X Wanted/Have = Wanted Where Wanted/Have = 1 or unity

6 Unit Factor Practice 1. Convert 34.5 centimeters into inches (2.54cm/1 in). 2. Convert 2376 grams into kilograms. 3. Convert 14.02 Liters into gallons (3.785L/1.000 Gal).

7 Uncertainty in Measurement A digit that must be estimated is called uncertain. A measurement always has some degree of uncertainty in the last digit reported.

8 Precision and Accuracy Accuracy refers to the agreement of a particular value with the true value. Precision refers to the degree of agreement among several measurements of the same quantity.

9 Significant Figures - Overview 1.Nonzero integers 2.Zeros leading zeros captive zeros trailing zeros 3.Exact numbers

10 Significant Figures - Details Nonzero integers always count as significant figures. 3456

11 Significant Figures - Details Zeros Leading zeros do not count as significant figures. Leading zeros do not count as significant figures.0.0486

12 Significant Figures - Details Zeros Captive zeros always count as significant figures. Captive zeros always count as significant figures.16.07

13 Significant Figures - Details Zeros Trailing zeros are significant only if the number contains a decimal point. Trailing zeros are significant only if the number contains a decimal point.9.300

14 Significant Figures - Details Zeros Trailing zeros are significant only if the number contains a decimal point. Trailing zeros are significant only if the number contains a decimal point.9300

15 Significant Figures - Details Zeros 9300 could be 2, could be 3, could be 4??? 9300 could be 2, could be 3, could be 4??? It is ambiguous. Therefore, Change it to Scientific Notation

16 Significant Figures - Details Zeros 9300 9300 2 sig figs 9.3 X 10 3 3 sig figs 9.30 X 10 3 4 sig figs 9.300 X 10 3

17 Significant Figures - Details Exact numbers have an infinite number of significant figures.Exact numbers have an infinite number of significant figures. 1 inch = 2.54 cm exactly

18 Rules for Significant Figures in Mathematical Operations Multiplication and Division: # sig figs in the result equals the number in the least precise measurement used in the calculation. 6.38  2.0 = 12.76 

19 Rules for Significant Figures in Mathematical Operations Addition and Subtraction: # sig figs in the result equals the number of decimal places in the least precise measurement. 6.8 + 11.934 = 18.734  _____________

20 Temperature Celsius scale = C Kelvin scale = K Fahrenheit scale = F

21 Temperature Scales Fahrenheit Scale, °F –Water’s freezing point = 32°F, boiling point = 212°F Celsius Scale, °C –Temperature unit larger than the Fahrenheit –Water’s freezing point = 0°C, boiling point = 100°C Kelvin Scale, K –Temperature unit same size as Celsius –Water’s freezing point = 273 K, boiling point = 373 K

22 Temperature

23 Type Unit Conversions What if I want to convert a mass unit into a volume unit? For example, can I convert grams into milliliters? g X --------- = mL g X ml/g = mL grams/milliliter is density

Download ppt "1 Measurements. 2 Nature of Measurement Measurement - quantitative observation consisting of 2 parts Part 1 - number Part 2 - scale (unit) Part 2 - scale."

Similar presentations