The Nature of Science

The Nature of ScienceThe Methods of Science What is science? 1. A method for studying the natural world 2. From Latin word scientia which means knowledge 3. Follows rules or natural patterns

Major Categories of ScienceEarth and Space Science (geology, meteorology, astronomy, etc.)Life Science (genetics, botany, ecology, zoology, etc.)Physical Science (matter & energy)

The sciences often overlapScience Explains Nature Explanations are modified as we learn more about the natural world often through new technology Pure Science vs. TechnologyPure science scientists who do experiments to learn more about the natural world.

Technology the application of science for practical uses; can be controversial (i.e., genetic engineering, stem cell research)Scientific Theories and LawsTheory must be able to explain observations clearly and consistently (based on knowledge gained from many observations); not a guess; experiments that illustrate the theory must be repeatable with the same result; must be able to predict results from the theory.

Law- a statement about what happens in nature and seems to be true every time; predicts what will happen in a given set of conditions, but does not explain how or why

A theory can explain a law.

Scientific Method- An organized set of investigation procedures which includes:

Stating a ProblemResearching & Gathering InformationForming a hypothesis (a testable prediction)Testing a hypothesis includes:making observationsbuilding or using a modelperforming an experimentDesigning a controlled experiment with multiple trialsGathering DataAnalyzing DataDrawing ConclusionsBeing Objective (eliminating bias)

Variable - a quantity that can have more than one value.

a. Independent Variable b. Dependent Variable c. Constants d. Control Variable - a quantity that can have more than one value.

a. Independent Variable - you change it b. Dependent Variable it changed c. Constants all of the things that remain the same d. Control a standard for comparison Making ObservationsQualitative observations using the 5 sensesQuantitative observations making measurements

Discover how long a foot is:1. Measure the distance across your classroom using your foot as a measuring device.2. Record your measurement and name your measuring unit.3. Repeat steps 1 and 2 for each group member.

Discover how long a foot is:1. Measure the distance across your classroom using your foot as a measuring device.2. Record your measurement and name your measuring unit.3. Repeat steps 1 and 2 for each group member.

Units of MeasurementA. Units and Standards 1. Standard - an exact quantity that people agree upon using for measurement 2. Cannot compare measurements without a standard 3. A measurement consists of a number and a unit.Measurement Systems

1. English System (feet, yards, inches, miles, pounds, etc.)

2. Metric system based on multiples of 10; devised by a group of scientists in the late 1700s.International System of Units (SI)

SI Units are used for consistency a. improved version of metric system in 1960sb. universally used and accepted by scientists world-wide c. Each type of measurement has a prefix & base unit (meter, Liter, gram)4. SI Prefixes Kilo Hecto- Deka Basic Unit deci- centi- milli- (k) (H) (D) (m, L, g, s) (d) (c) (m)103 102 101 100 10-1 10-2 10-35. SI Standards of MeasurementQuantity MeasuredUnitSymbolLengthmetermMasskilogram kTimesecondsTemperaturekelvinKAmount of substancemolemolElectric CurrentampereAIntensity of LightcandelacdRulerLengthWidth1 234DataMeasure the length and width of an index card using the least precise to the most precise measuring device.

7.6. Significant Figures All of the numbers in a measurement known for certain plus an estimated digit.

(See Handout)

All digits 1-9 are significant. Example: 129 has 3 significant digits

2. Zeros between significant digits are always significant. Example: 5007 has 4 significant digits

3. Trailing zeros in a number are significant only if the number contains a decimal point.Examples: 100.0 has 4 significant digits 100. has 3 significant digit 100 has 1 significant digit 4. Zeros in the beginning of a number whose only function is to place the decimal point are not significant.Example: 0.0025 has 2 significant digits 0.004 has 1 significant digit

5. Zeros following a decimal significant digit are significant.Example: 0.000470 has 3 significant digits 0.47000 has 5 significant digits

ATLANTIC-PACIFIC RULEIf the decimal is ABSENT, start with the first non-zero number on the ATLANTIC side and count going LEFT.If the decimal is PRESENT, start with the first non-zero number on the PACIFIC side and count going RIGHT.

Precision vs. Accuracy

Scientific NotationHow to write a very large number, such as

46,350,000 = 4.635 x 107 coefficient Move the decimal until you get to a number 1- 9.9The number of times moved is equal to the exponent.

When the number is less than one, the exponent will be negative.

0.000224 = 2.24 x 10-4Scientific Notation Practice425 cm = 36000 cg = 0.00098 m = 0.0135 kg =1000.345 g = Scientific Notation Answers425 cm = 4.25 x 102 cm36000 cg = 3.6 x 104 cg0.00098 m = 9.8 x 10-4 m0.0135 kg= 1.35 x 10-2 kg1000.345 g = 1.000345 x 103 g

Calculations with Scientific Notation

When adding or subtracting numbers in scientific notation, the power of 10 must be the same. Example: 3.6 x 103 + 5.2 x 102 = 3.6 x 103 + 0.52 x 103 = 4.1 x 103 OR 36 x 102 + 5.2 x 102 = 41.2 x 102 = 4.1 x 103When multiplying numbers in scientific notation, multiply the coefficients, then ADD exponents.

Examples:1. (3 x 102 )(2 x 105) = 6 x 107 2. (4 x 104 )(5 x 105) = 20. x 109 = 2 x 101 x 109 = 2 x 1010 When dividing numbers in scientific notation, divide the coefficients, then SUBTRACT exponents. Examples1) 4 x 103 = 2 x 103-2 = 2 x 101 2 x 102

2) 4 x 10-3 = 2 x 10 -3- -2 = -3 +2 = 2 x 10 -1 2 x 10-2 Dimensional AnalysisHow many seconds are in one year?8. Converting Between SI UnitsDimensional Analysis is a method of problem-solving that focuses on the units used to describe matter.

9. Dimensional Analysis

A conversion factor -a ratio of equivalent values Example, 1 dozen = 12 eggs could be written:

1 dozen or 12 eggs 12 eggs 1 dozen

Examples:1) 30 eggs = ______ dozen

30 eggs x 1 dozen = 2.5 dozen 12 eggs 2) 1.5 dozen = ______ eggs1.5 dozen x 12 eggs = 18 eggs 1 dozen

3) If you buy 13.3 gallons of gasoline at $2.899/gallon, how much do you pay?

13.3 gal x $2.899 = $ 38.56 1 gal

(if it had been $2.89/gallon, it would be $38.44)Kilo Hecto- Deka Basic Unit deci- centi- milli-

4) 1.225 L = ________ mL

1 L = 1000 mL

1.225 L x 1000 mL = 1225 mL 1 L

5) 5400 mg = ______ g

1000 mg = 1 g

5400 mg x __1 g__ = 5.4 g 1000 mg

Kilo Hecto- Deka Basic Unit deci- centi- milli-

Measuring Distance 1. Length is the distance between 2 points. 2. Choosing a Unit of Length a. unit chosen depends on the size of the object.

Measuring Volume 1. Volume the amount of space occupied by an object 2. Volume formulas: Rectangular Solids: V = lwh Cylinder: V = r2h Sphere: V = 4 r3 3

Measuring Liquid Volume

a. Usually expressed in Liters (L) or milliliters (mL)

b. 1 cc = 1 cm3 = 1 mLConverting from Liters to cm31.5 L x 1000 mL x 1 cm3 = 1500 cm3 1 L 1 mLMeasuring Matter 1. Mass a measurement of the quantity of matter in an object. The kilogram is the basic unit of mass in SI.

Density - the mass per unit volume of a material. ( D = m/v)MaterialDensity (g/cm3)MaterialDensity(g/cm3)hydrogen0.00009aluminum2.7oxygen0.0014iron7.9water1.0gold19.3Derived Units a. A unit obtained by combining different SI units b. Examples: 1) density: g/cm3 2) volume: m3 F. Measuring Time & Temperature 1. Time - the interval between 2 events - SI unit of time is the second (s)

Temperature- measure of the average kinetic energy of the particles of matter

- SI unit of temp. is Kelvin (K) - Absolute Zero: 0 K is - 273C ( 273 lower than freezing pt. of water) - Do not use degree symbol with K. - Laboratory thermometers use Celsius scale- Fahrenheit scale will not be used the science lab

Temperature Conversions K= C + 273 (Notice Kelvin does not have )

C = 5 (F-32) 9

F = 9 C + 32 53. Percent Error Calculation% Error = |Accepted Value Experimental Value | x 100 | Accepted Value |

Accepted Values for pure substances can be found in the Handbook of Chemistry and Physics.

Experimental Values are determined from measurements taken during an experiment.

Communicating with Graphs Graph - A visual display of information or data Line Graphs

1. Can show any relationship where the dependent variable changes to a change in the independent variable.

2. Often show changes over time.

3. Independent Variable is plotted on x-axis

4. Dependent variable is plotted on y-axis 5. Refer to the Components of an Excellent Graph Bar Graphs

Useful for comparing information collected by counting.Circle Graphs Used to show how some fixed quantity is broken down into parts.

Making a Circle (Pie) Grapha. Use a protractor to make a circle graph. 1) Determine the percentage of each component. (Make sure all %s add up to 100) 2) Change percentage to a decimal. 3) Multiply decimal by 360 4) Draw a circle. Draw a line across the diameter. 5) Use the protractor to measure each angle.