# Ch. 2 Sec. 1 Measures in Science.

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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 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

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 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 = m 2.278 x 1011m Mass of electron = kg 9.11 x 10-31kg

Express in Sci. Notation
5800 0.004

Express in Sci. Notation

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

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  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 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 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

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