1. Ch. 2 Sec. 1
Measures in Science

2. Metric System & SI Units
French Scientists adopted metric system in 1795
Metric system uses powers of 10
10 millimeter = 1 centimeter
10 centimeter = 1 decimeter
10 decimeter = 1 meter
There are 7 base units

3. Base units Chart SI Base Units Base Quantity Base Unit Symbol Length
Meter m
Mass
Kilogram kg
Time
Second s
Temperature
Kelvin K
Amount of Substance
Mole
mol
Electric Current
Ampere A
Luminous Intensity
Candela cd

4. Derived units Combination of the base units
Speed or velocity = meters per second, m/s
Energy = joule, kg m2/s2

5. SI Unit Prefixes Prefix Symbol Multiplier Sci. Notation Pico p
1/1,000,000,000,000
10-12
Nano n
1/1,000,000,000
10-9
Micro
1/1,000,000
10-6
Milli m
1/1,000
10-3
Centi c
1/100
10-2
Deci d
1/10
10-1
Kilo k
1000
103
Mega M
1,000,000
106
Giga G
1,000,000,000
109
Tera T
1,000,000,000,000
1012

6. Scientific Notation
Able to make using really large or small numbers easier
Expressing decimal numbers in powers of 10
N x 10n
Move decimal point until only one non-zero digit remains
Count the number of spaces and use that as exponent
Earth to Mars = m
2.278 x 1011m
Mass of electron = kg
9.11 x 10-31kg

7. Express in Sci. Notation
5800
0.004

8. Express in Sci. Notation

9. Converting Units What is the equivalent in km of 670 m?
1 km = 1000 m
(1000 m)/ (1 km) = 1
Using a Conversion Factor you can determine the relationship between two units
Multiplier equal to one
670 m = (670 m) (1 km / 1000 m)
(670 m x 1 km) / 1000 m = km
Label units will cancel out

10. Converting Units Practice
1.1 cm  meters
76.2 pm  millimeters
2.1 km  meters
2.278 x 1011 m  kilometers
147 g  kilograms
11 Mg  kilograms
7.23 µg  kilograms
478 mg  kilograms

11. Converting Units Practice
1.1 cm  1.1 x 10-2 m
76.2 pm  7.62 x 10-8 mm
2.1 km  2.1 x 103 m
2.278 x 1011 m  x 108 km
147 g  1.47 x 10-1 kg
11 Mg  1.1 x 104 kg
7.23 µg  7.23 x 10-9 kg
478 mg  4.78 x 10-4 kg

12. Adding and Subtracting in Sci. Notation
When adding or subtracting, make sure the powers of 10 are the same (10N)
4 x x 108
(4 + 3) x 108
7 x 108
(4.1 x 10-6) – (3.0 x 10-7)
(4.1 x 10-6) – (0.30 x 10-6)
(4.1 – 0.30) x 10-6
3.8 x 10-6

13. Multiplying & Dividing in Sci. Notation
Multiply or divide the values and the units
Add (if multiplying) or subtract (if dividing) the exponents
(4 x 103 kg)(5 x 1011 m)
(4 x 5) x kg•m
20 x 1014 kg m  2 x 1015 kg m
(8 x 106 m3) / (2 x 10-3 m2)
(8/2) x 106 – (-3) m(3-2)
4 x 109 m
If units have powers, add or subtract accordingly