Physical Science Methods and Math Describing Matter The Scientific Method Measurements and Calculations 1

Topics covered Measuring - Base Units Calculating - Derived Units Prefixes Scientific Notation – Calculations Measuring and Significant Figures – Precision and Accuracy Manipulating Equations Dimensional Analysis (Conversions) The Scientific Method Lab Safety 2

DESCRIBING MATTER 3

Length Definition Measured with SI base unit 4

Prefixes Used for very large or very small amounts 5

Matter Anything that has volume and mass 6

Volume Defined Units – Liter – Cubic meter 7

Determining Volume Of liquid Instrument Meniscus – how to read 8

The Volume of an irregular shaped object Water displacement method 9

Calculating volume Of a block Of a cylinder 10

Mass Define Measured with SI base unit 11

How to find the mass of a liquid Subtraction method 12

Weight is not mass A measure of the force of __ The SI unit of force is the ___ Measured with a 13

Quantity Something that has magnitude, size, or amount How much A number (and a unit) 14

Qualitative vs. Quantitative Color texture smell taste beauty 15

Sheldon Quantifies Everything 16

Unit A quantity adopted as a standard of measurement 7 SI Base Units, called so because they are Measured 17

Temperature Define Measure with SI unit 18

Temperature Scale Conversions 19

Converting Units: Dimensional Analysis Used to convert units Multiply by equalivant (multiplying by 1) The unit you want cancelled out goes... Multiply by top number & divide by bottom number 20

Derived Units Combinations of fundamental (base) units Calculated Note: The symbol for density is the Greek letter p pronounced rho 21

Density Mass per unit of volume 22

Percent Error A way to express how far a laboratory value is from the commonly accepted value 23

Directly Proportional When one variable goes up, the other goes up proportionally E.g.. temperature and volume of a gas 24

Inversely Proportional When one variable goes up, the other goes down proportionally E.g.. Pressure and volume of a gas Graph called a hyperbola 25

The Nature of Science 26

The Nature of Science Science ask 3 basic questions: What is there? How does it work? How did it come to be that way? 27 “The most amazing thing Humans do is ask questions”

Science Includes A Method by which knowledge is attained The body of knowledge What is done with the knowledge (technology) 28

Scientific Method The goal is to correctly answer the three questions There is no one method of science, it is not linear A body of techniques Consist of systematic observation and measurement Is self-correcting 29

Scientific Evidence is Empirical Evidence Information gained by observation and experiment Is reproducible and verifiable Non-dogmatic

Teleology The attribution of purpose to natural phenomena Science rejects teleology 31

Observation Any information detected by the 5 senses

Fact Verified by repeatable observation or measurement (sometimes experiments) – Empirical

Imply vs Infer ImplicationInference To conclude from evidence To express something indirectly Sheldon explains Implying and Inferring b1CtIATw&spfreload=10

Hypothesis A possible answer to a question, usually based on observations Must be testable or falsifiable Usually an “If … then …” statement

Law Newton’s Laws Law of Gravity A Description of an event in Nature Usually mathematical Does NOT explain why it happens

Theory An explanation of facts observations, and laws Make testable (falsifiable) predictions Changeable (non-dogmatic) Must be an explanation based on laws of nature and empirical evidence “Theories are the most reliable, most rigorous, and most comprehensive form of knowledge that humans possess.”

Models A visual, verbal, or mathematical representation used to explain how phenomena occur or how data or events are related 38 Models are Theories

MEASUREMENTS AND CALCULATIONS IN SCIENCE 39

Accuracy and Precision 40

Uncertainties in Measurement All measurements have some degree of uncertainty – Human error – Method error – Limits of the instrument 41

Accuracy A description of how close a measurement is to the true value of the quantity measured 42

Precision The exactness of a measurement How close several measurements are to each other 43

Precision Reproducibility: The degree of exactness to which a measurement can be reproduced. Repeated measurements show the same results. Accuracy Correctness: The extent to which a measured value agrees with the standard value. How close it is to correct or true value. 44 A measurement system is considered valid if it both accurate and precise

Significant Digits (Figures) The number of digits that are valid for a measurement All digits known plus one estimated digit 45

How many Sig Figs does a number have? An essential skill for Chemistry and Physics Calculators do not determine sig figs 46

Rules for determining how many Sig Figs a number has? Rule 1 47

Rules for zeros All zeros between non-zeros are significant Three sig figs

Rules for Zeros continued Zeros are significant if they are to the right of both a decimal and another sig fig Two sig figs 49

Zero Rules cont. Zeros used solely for spacing the decimal are not significant 50

Decimal at the end sig fig sig figs The decimal makes the zeros significant Also, a line over the zero 51

Exact values have infinite sig figs Count values ( a dozen is exactly 12) Conversions (100 cm = 1 m) 52

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Operations using Sig Figs An answer can not be more precise than the least precise measurement 54

Sig Figs: Addition and Subtraction 55 The result is rounded off to the least precise number (least decimal places)

Sig Figs: Multiplication and Division The answer is rounded off to the factor with the least number of sig figs 56

SCIENTIFIC NOTATION AND ARITHMETIC OPERATIONS 57

Scientific Notation A shortened form for writing very large or very small numbers One non-zero digit to the left of the decimal Exponent 58

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Addition 60 The powers of 10 must be made the same

Subtraction 61

Multiplication Multiply the values of M, then add the exponents 62

Division Divide the values of M, then subtract the exponents 63

Manipulating Equations Using Algebra d=st What is the formula for s? For t? 64

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