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 non- living 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 10 8 m/s

Example 2 Example: speed of a snail Numeric value: m/s In scientific notation: 8.6 x 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 10 8 m/s) x (5.0 x 10 2 s) Step 1: Multiply: 3 x 5 = 15 Step 2: Add exponents: = “Raw” answer: 15 x m Final answer: 1.5 x m

Dividing in Scientific Notation Rule: Divide the numbers that appear before the exponential terms and SUBTRACT the exponents. 1.5 x m 3.0 x 10 8 m/s Step 1: Divide numbers  1.5/3 = 0.5 Step 2: Subtract exponents  11-8 = 3 Raw answer: 0.5 x 10 3 s Final answer: 5.0 x 10 2 s

Practice Problem # 1 (7.6 x m) x (1.5 x 10 7 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 3 Raw answer: 11.4 x 10 3 m 2 Final answer: 1.14 x 10 4 m 2

Practice Problem # / 29 Step 1: Convert to scientific notation 5.3 x / 2.9 x 10 1 Step 2: Divide the numbers that appear before the exponential terms 5.3 / 2.9 = 1.8 Step 3: Subtract the exponents – 10 1 = 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 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/cm 3

Measuring Temperature Thermometer: an instrument that measures temperature. Fahrenheit: water freezes at 32 o and boils at 212 o. Celsius: water freezes at 0 o and boils at 100 o. Note: A degree Celsius is almost twice as large as a degree Fahrenheit.

Converting between C and F Celsius: ( o F- 32) x.55 Fahrenheit: ( o C x 1.8) + 32 o

Practice Problem 1 Question: 32 o C is equivalent to what Fahrenheit temperature? Answer: 89.6 o F

Practice Problem 2 Question: 95 o F is equivalent to what Celsius temperature? Answer: 34.7 o C

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 o F). In o C, this temperature is

Converting between C and K K = o C See Figure 19 on p. 20.