Chapter 3 AScientific Measurements Basic Terms Measurement Comparison

Chapter 3 AScientific Measurements

Basic Terms • Measurement – Comparison of dimension of an object to a standard – Example- measuring how tall (dimension) you (object) are in centimeters (standard) • Dimension – Property that can be measured – Example- height (how tall you are) • Standard – Known quantity that everyone agrees to use – Example- the metric system

Basic Terms • Instrument – What you use to measure – Example- ruler • Unit – Segment of dimension used for measuring – Example- centimeter • Calibrated scale – Markings on an instrument to tell you how many units something is

Measured Data • Data - collected and observed information • 2 types: – Quantitative- numerical data (numbers) – Qualitative- descriptive data (words) • Scientists prefer quantitative, because it has no observational bias (people won’t say different things just because they like or don’t like something)

Measured Data • Must have 2 things: – Number – Unit

Metric System • Standard system of measuring that includes meters and grams – Metric System • SI- International System of Units – Has base units, units everyone uses • • Length- meter (m) Mass- kilogram (kg) Time- second (s) Amount of something- mole (mol)

Metric System • Metric system also has “prefixes” • Instead of saying “ 1 thousand grams”, we say “ 1 kilogram”

Metric System Prefix Symbol Meaning Factor Exponential (discuss later) giga- G- Billion 1, 000, 000 109 mega- M- Million 1, 000 106 kilo- k- Thousand 1, 000 103 ---- Normal 1 100 centi- c- Hundreth 0. 01 10 -2 milli- m- Thousandth 0. 001 10 -3 micro- μ- Millionth 0. 000 001 10 -6 nano- n- Billionth 0. 000 001 10 -9

Unit Conversions • Conversion means changing everything so it is the same unit • 2 m, 200 cm, and 2000 mm… Same? – 100 cm = 1 m • (show math on the board) – 200 cm = 2 m. SAME! – 1000 mm = 1 m • (show math on the board) – 2000 mm =2 m. SAME!

Practice Problem • How many milliliters are there in a 2 L soft drink? 1 L = 1000 m. L 1 L 2 L x 1000 m. L = 2000 m. L 1 L

Practice Problem • Which contains more mass, a 350 g box of chocolates or a 3. 5 kg box of chocolates? 1 kg = 1000 g 3. 5 kg x 1000 g = 3500 g 1 kg The 3. 5 kg box contains more!