I.  Measurements
    A. The importance of measurements in experiments
    B. Units of measurement
    C. Standard units and standardized systems of units
            1. SI
            2. cgs
            3. American Conventional
    D. Fundamental units within each system
            1. Must be able to measure length, amount (mass) and time
            2. Summary Table
    E. Prefixes
            1. Powers of 10 that are multiples of 3 have prefixes
            2. Some other powers also have prefixes, but generally only centi- is used anymore
            3. See text table 1.4 in your textbook
    F. Unit Analysis
    G. Significant figures
            1. When is a digit significant?
            2. Multiplying and dividing
            3. Adding and subtraction
    H. Unit conversions
            1. Technique is useful for other applications
            2. Make a fraction equal to 1 so the value itself doesn't change
            3. Examples
    I. Problem solving
            1. Important steps -- show all possible, think about all even if they can't be shown
            2. See list of steps on page 16 in the textbook
 

Examples:
 

1) The following are the base units for each system and quantity
 

System	Length	Mass	Time
SI (mks)	meter (m)	kilogram (kg)	second (s)
cgs	centimeter (cm)	gram (g)	second (s)
American Standard	foot (ft)	slug	second (s)

 

2) When is a digit significant?

Number	Number of Significant Digits	Comments
1234	4	No zeros, so all significant
0.234	3	Leading zero is not significant
0.00234	3	Leading zeros are not significant
0.0023450	5	Last zero is significant, leading zeros are not
1000	1 - 4	Not clear so use scientific notation: 1 x 103 has 1 sig fig; 1.0 x 103 has 2; 1.00 x 103 has 3; and 1.000 x 103 has 4. I would assume 1 sig fig without any scientific notation
1.000	4	All the zeros follow the decimal point and another sig fig, so all are significant

3) Significant figures in calculations:
 

Multiplying or dividing - count number of significant figures, round to the least number
 

(2.53)(7.97532) = 20.1775596 ~ 20.2

3 sf        6 sf                                  Result limited to 3 sf
 

Adding or subtracting - look at place value of last significant figure, round to largest decimal value
 

   12.3             tenths place - largest decimal value
 154.98           hundredths place
0.7596  ten thousandths place
 168.0396 ~ 168.0     round to tenths place
 

4) Convert 12.50 inches to cm:

12.50 in x 2.54 cm/1 in = 31.75 cm    the result should have the same number of sf as original number

Convert 100.0 km/h to m/s

100.0 km/h x 1000 m / km x 1 hr / 3600 s = 27.78 m/s