Science Process, Graphing, SI System Unit 1 Science Process, Graphing, SI System

Science Pure Science versus Technology Pure science is the study of the natural world Technology is applied science. Use of pure science knowledge to make an application or make something new.

Scientific Theories and Laws Scientific Theory- is an explanation of a natural event that has been tested by repeated observations. Scientific Law- states a repeated observation about nature. Has been tested and always holds true.

Description versus Math Qualitative Statements: describe events in nature. Qualities Example: the effects of gravity on falling bodies. Data: collected in the form of statements describing observations Quantitative Statements: laws and theories stated as mathematic equations. Mathematics is the language of science that is universal. Data: Use of equations, measurements, numbers

Models Model is a representation of an object or event. Example: cell model, model of an atom, molecule

Critical Thinking! Critical Thinking: applying logic and reason to solve problems. Experimental Design Format: Observe Question Hypothesis Test/Experiment Collect/Analyze Data Draw Conclusions

Observations and Inferences Observations can be direct or indirect. Direct: made by using the 5 senses. What you see, hear, taste, touch, or smell. Indirect: Made by making a measurement Examples: length, temperature, mass, volume Inferences: educated guesses that explain an event. Basis for hypothesis statements

How Do You Get Started…… Make an Observation and then ask a Question. Question: Identifies the problem Only asks one thing at a time. Stated clearly Looks for a specific outcome.

Variables and Controls Variable: part that is changed in an experiment Independent variable: The part that you purposely change in an experiment. Graphed on the x-axis in line graphs (horizontal axis) Dependent Variable: The part that changes as a result of what was manipulated. Graphed on the y-axis in line graphs (vertical) Control: experimental set-up where no factors are changed. Comparison Group.

Hypothesis A possible explanation for a set of observations or answer to a question If/Then format A formal hypothesis does not use first person terminology No personal pronouns. It should include the independent variable (factor that is changed) followed by the dependent variable (what changed in response).

Hypothesis Statement Format If (the independent variable) is (describe how you change it), the (dependent variable) will (describe the effect). If __ is __, then ___ will ___.

Setting up the Experiment… Procedure: Well defined set of step by step instructions. ( No personal Pronouns) Includes an experimental group set-up to test (independent variable change). Includes a control group. Identifies the constants Constant- factors that are given to both the experimental group and the control group. **Remember that only one factor will be different for the experimental group. All other factors should be the same.

Collecting Data….. Qualitative: Description in the form of a paragraph, non measured, can be in a chart. Quantitative: Measured values, in the form of charts and graphs

Types of Graphs Line Graph: usually used to show changes over time, or data that changes Bar Graphs: used when comparing data for several different individual items or events. Pie Chart: used when comparing parts of a whole

Graphing Data….. Remember: independent variable should be graphed on the x-axis dependent variable on the y-axis. y x

Drawing Conclusions…. Paragraph format: Restatement of Hypothesis Claim: based on data Evidence: site specific data Reason statement: give reason for claim Formal writing format based on fact. Not opinion based No personal Pronouns

SI System Based on the metric system Units of 10 International use by scientist to communicate data. 7 Base Units Length meter m Mass kilogram kg Time second s Temperature kelvin K Electric Current ampere A Amount of a substance mole mol Luminous intensity candela cd

Derived Units Combinations of the base units: Examples: speed, density, weight, force, area, volume

SI Prefixes…. To avoid the use of a lot of decimal places and zeroes we use metric prefixes to express very large and very small amounts. Are all multiples of 10

Common Metric Prefixes Memorize the basics and their power of 10 Milli 0.001 m Centi 0.01 c Deci 0.1 d Base 1.0 Base Unit (Meter, Liter, Gram) Deka 10 dK Hecto 100 h Kilo 1000 K

Prefix Symbol Numerical Exponential Multiplier Prefix Symbol Numerical Exponential Yotta Y 1,000,000,000,000,000,000,000,000 1024 zetta Z 1,000,000,000,000,000,000,000 1021 exa E 1,000,000,000,000,000,000 1018 pta P 1,000,000,000,000,000 1015 tera T 1,000,000,000,000 1012 giga G 1,000,000,000 109 Mega M 1,000,000 106 kilo k 1,000 103 hecto h 100 102 deca da 10 101 no prefix means: 1 100 deci d 0.1 10¯1 centi c 0.01 10¯2 milli m 0.001 10¯3 micro µ 0.000001 10¯6 nano n 0.000000001 10¯9 pico p 0.000000000001 10¯12 femto f 0.000000000000001 10¯15 atto a 0.000000000000000001 10¯18 zepto z 0.000000000000000000001 10¯21 yocto y 0.000000000000000000000001 10¯24

Common Measurements Length: The straight-line distance between two points Mass: a measure of the amount of matter in an object Volume: a measure of the space an object takes up or the capacity of a container Weight: the force that gravity pulls on a quantity of matter.

Temperature Celsius to Kelvin Conversions: Celsius and Fahrenheit C = 5/9(F-32) F = (9/5C) + 32

Dimensional Analysis and Conversions If you are converting to a smaller unit, multiply. If you are converting to a larger unit, divide. 100cm 1.85m x ---------- = 185 cm 1m

Keys For Success With Dimensional Analysis Must Use Correct Conversion Factor ** know the prefixes and what they stand for Don’t forget to treat the Units of Measure just like numbers (Canceling out the U/M’s) Set up equations so X is a numerator.

Conversion Factors of One 1 cm3 = 1ml of space 1g of water takes up 1ml of space or 1 cm3

Scientific Notation Scientific Notation: a value written as a simple number multiplied by a power of 10.

Scientific Notation Steps Shortcut Steps: Put the decimal between the first two numbers. Count the number of places you moved the decimal and that becomes the power of 10. When a quantity smaller than one is converted the power becomes negative. (The decimal moves to the right)

Examples of Scientific Notation 0.00048 cm = 4.8 x 10-4cm 35,000,000 mm = 3.5 x 107mm

Calculators and Scientific Notation E values Example: 3.12 x 104 3.12E4 The E value is the exponent power of 10.

Significant Figures Significant Figures: the digits in a measurement that are known for certain. Precision: The degree of exactness of a measurement. Depends on the instrument used. Accuracy: the extent to which a measurement approaches the true value. Rounding to get significant figures: Always round to the even number. Example: 3.25 = 3.2

Sig Fig Rules Only keep the number of digits in a number that are known to be accurate When doing math, the answer can not be more precise that the least precise measurement used in the calculation.

Sig Fig’s: Why???? Precise measurement can be important! Historical Perspective: Hubble Telescope Save time and computations of needless numbers Why multiply 1.3485676879m when the measurement is only accurate to 1.34m?

Instrument Precision Triple Beam Balance = 0.1g Meter Stick = 1mm Measure of Mass Meter Stick = 1mm Length Time = 0.01 s Second Graduated Cylinder = 0.1mL to 1mL depending on size used. Volume Can also be solid volume = 0.001m or 1mm Thermometer = 1C

SI Rules All measurements must have a unit of measure attached to the end. Zero’s mean something! No naked decimals Put a zero in front 0.5cm Zeroes at the end indicate the accuracy of the measurement 5.6 is less precise than 5.600 but only put the 00’s if measurement is that precise.