Ch. 2 Sec. 1
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Transcript Ch. 2 Sec. 1
Ch. 2 Sec. 1
Measures in Science
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
Base units Chart
Base Quantity
Length
Mass
Time
Temperature
Amount of Substance
Electric Current
Luminous Intensity
SI Base Units
Base Unit
Meter
Kilogram
Second
Kelvin
Mole
Ampere
Candela
Symbol
m
kg
s
K
mol
A
cd
Derived units
Combination of the base units
Speed or velocity = meters per second, m/s
Energy = joule, kg m2/s2
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
µ
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
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 = 227 800 000 000m
2.278 x 1011m
Mass of electron = 0.000 000 000 000 000 000 000 000 000 000 911
kg
9.11 x 10-31kg
Express in Sci. Notation
5800
450 000
302 000 000
86 000 000 000
0.000 508
0.000 000 45
0.0003600
0.004
Express in Sci. Notation
5800 = 5.8 x 103
450 000 = 4.5 x 105
302 000 000 = 3.02 x 108
86 000 000 000 = 8.6 x 1010
0.000 508 = 5.08 x 10-4
0.000 000 45 = 4.5 x 10-7
0.0003600 = 3.600 x 10-4
0.004 = 4 x 10-3
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 = 0.670 km
Label units will cancel out
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
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 2.278 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
Adding and Subtracting in Sci. Notation
When adding or subtracting, make sure the powers of 10 are
the same (10N)
4 x 108 + 3 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
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 103 + 11 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