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Chapter 1 Science Skills Science and Technology • “Science” derives from Latin scientia, meaning “knowledge” • Science: a system of knowledge and the methods used to find that knowledge. • Technology: the use of knowledge to solve practical problems. • Difference: Science expands knowledge; technology applies knowledge. Physical Science • Science: divided into social and natural • Natural science: 3 branches— physical, Earth and space, life • Physical science: a branch of natural science that focuses on nonliving things • 2 main areas: chemistry and physics Chemistry and Physics • Chemistry: the study of the composition, structure, properties, and reactions of matter • Physics: the study of matter and energy and the interactions between the two through forces and motion Earth Sciences • Geology: the study of the origin, history, and structure of earth. • Astronomy: the study of the universe beyond Earth, including the sun, moon, planets, and stars Life Sciences • Biology: the study of living things • Bios: Greek for “life” • -ology: “study of” Scientific Method • Definition: an organized plan for gathering, organizing, and communicating information. • Goal: to solve a problem or to better understand an observed event Steps in the Scientific Method (1) Make observations (2) Ask a question (3) Form a hypothesis (4) Test the hypothesis/collect data (5) Analyze data (6) Conclusions Definitions • Observation: information obtained through the senses • Hypothesis: a proposed answer to a question • Scientific theory: a well-tested explanation for a set of observations or experimental results • Note: Theories are never proved • Scientific law: a statement that summarizes a pattern found in nature Models • Model: a representation of an object or event • Models make it easier to understand things that might be too difficult to observe directly Scientific Notation • Scientific notation: a way of expressing a value as the product of a number between 1 and 10 and a power of 10. Example 1 • Example: speed of light • Numeric value: 300,000,000 m/s • In scientific notation: 3.0 x 108 m/s Example 2 • • • • Example: speed of a snail Numeric value: .00086 m/s In scientific notation: 8.6 x 10-4 m/s Note: If the number you begin with is less than 1, your exponent will be negative. Multiplying in Scientific Notation • Rule: Multiply the numbers that appear before the multiplication signs and ADD the exponents. • (3.0 x 108m/s) x (5.0 x 102s) • Step 1: Multiply: 3 x 5 = 15 • Step 2: Add exponents: 108 + 102 = 1010 • “Raw” answer: 15 x 1010 m • Final answer: 1.5 x 1011m Dividing in Scientific Notation • Rule: Divide the numbers that appear before the exponential terms and SUBTRACT the exponents. • 1.5 x 1011m 3.0 x 108 m/s • Step 1: Divide numbers 1.5/3 = 0.5 • Step 2: Subtract exponents11-8 = 3 • Raw answer: 0.5 x 103s • Final answer: 5.0 x 102s Practice Problem # 1 • (7.6 x 10-4 m) x (1.5 x 107 m) = ? • Step 1: Multiply the numbers that appear before the multiplication signs. • 7.6 x 1.5 = 11.4 • Step 2: Add the exponents. • 10-4 + 107 = 103 • Raw answer: 11.4 x 103 m2 • Final answer: 1.14 x 104 m2 Practice Problem # 2 • • • • • • • • 0.00053 / 29 Step 1: Convert to scientific notation 5.3 x 10-4 / 2.9 x 101 Step 2: Divide the numbers that appear before the exponential terms 5.3 / 2.9 = 1.8 Step 3: Subtract the exponents 10-4 – 101 = 10-5 Answer: 1.8 x 10-5 Bell-ringer • What is a Kelvin? Units of Measurement • For a measurement to make sense, it requires both a number and a unit. • Scientists do not measure in inches, feet, and degrees Fahrenheit. • Scientists use a set of measuring units called SI SI Definitions • Length: the straight-line distance between two points • Mass: the quantity of matter in an object or sample • Volume: the amount of space taken up by an object • Density: the ratio of an object’s mass to its volume (D = m/v) SI Base Units • • • • • Length meter (m) Mass kilogram (kg) Temperature Kelvin (K) Time second (s) Amount of substance mole Significant Figures • Significant figures: all the digits that are known in a measurement, plus the last digit that is estimated. • The fewer the significant figures, the less precise the measurement is. • The precision of calculated answer is limited by the least precise measurement used in the calculation. Significant Figure Problem • A piece of iron weighs 34.73 grams. Its volume is 4.42 cubic centimeters. • (a) What is its density? • Answer: D = m/v = 34.73/4.42 • (b) How many significant figures should the answer contain? • Answer: 3 • Why: Because the least precise measurement (volume) has 3 significant figures. • Final answer: 7.86 g/cm3 Measuring Temperature • Thermometer: an instrument that measures temperature. • Fahrenheit: water freezes at 32o and boils at 212o. • Celsius: water freezes at 0o and boils at 100o. • Note: A degree Celsius is almost twice as large as a degree Fahrenheit. Converting between C and F • Celsius: (oF- 32) x .55 • Fahrenheit: (oC x 1.8) + 32o Practice Problem 1 • Question: 32oC is equivalent to what Fahrenheit temperature? • Answer: 89.6oF Practice Problem 2 • Question: 95oF is equivalent to what Celsius temperature? • Answer: 34.7oC Kelvin • The SI base unit of temperature is the kelvin (K). • A temperature of 0 K [absolute zero] refers to the lowest possible temperature that can be reached (over 500 below 0 in oF). • In oC, this temperature is -273.15. Converting between C and K • K = oC + 273 • See Figure 19 on p. 20.