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Chapter 1: Introduction to Science Section 1: The nature of science
Mr. Stripling Physical Science
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What is Science? Science is a method for studying the natural world.
It is a process that uses observation and investigation to gain knowledge about events in nature.
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Branches of Science Draw in your notes Science Social Natural
Life Science Biology Earth Science Astronomy Geology Physical Science Physics Chemistry
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Branches of Science Branches of Science Three MAIN BRANCHES
Life science deals with living things. Earth science investigates Earth and space. Physical science deals with matter and energy.
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Science vs. technology Science seeks to understand the natural world
Explains what is going on around us Technology is the application of science to help people.
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Technology Meets human needs, makes things easier, solves problems
Doesn’t always follow science, however, sometimes the process of discovery can be reversed. Science and technology do not always produce positive results.
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Scientific laws and theories
Theory – similar to a guess but with a focus on WHY something happens. It must pass several tests to be usable. Seeks to explain many different laws. Scientific Law – describes a process in nature that can be tested with repeated experiments. An observation about nature; a summary of a natural event Theories Must explain observation clearly and consistently Experiment must be repeatable Must be able to predict results from the theory
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Describing physical events with math Example: GRAVITY
Qualitative statement – describes something with words Quantitative statement – explains scientific laws and theories with equations Area of a rectangle equation: A = l x w Universal gravity equation: Mathematics is the same language around the world!
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Models A scientific model is a representation of an object or event that can be studied to understand the real object or event. Can be used to represent things that are too small, too big, or too complex to study easily.
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Name some examples of models that you use every day
With your group brainstorm as many commonly used models as you can.
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Exit card #2 Compare the two branches of physical science.
Explain how science and technology depend on each other and how they differ from each other. Define scientific law and give an example. Compare scientific law and scientific theory. Explain why a scientific theory might be changed. Describe how a scientific model is used and give an example of a scientific model.
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Section 2: The way science works
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The scientific method
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The scientific method is a process for experimentation
that is used to explore observations and answer questions. Scientists use the scientific method to search for cause and effect relationships in nature. In other words, they design an experiment so that changes to one item cause something else to change in a predictable way. 14
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Testing a hypothesis Controlled experiments are used to test a hypothesis A variable is a factor that changes in an experiment in order to test a hypothesis
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Experiments test ideas
Experiments are not failures when they fail to produce the desired results A hypothesis can be revised “Failed” experiments should be published so that they can be peer reviewed Why should “failed” experiments be published?
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Units of measurement Scientists use standard units of measure that together form the International System of Units, aka the SI System Used by scientists around the world Why do you think that scientists use the SI system?
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Basic Types of Measurement
Length: measures distance between objects Volume: measures the amount of space something takes up Mass: measures the amount of matter in an object Other Types of measurement include: time temperature density PH
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Measurement System Comparisons
ENGLISH SI SYSTEM LENGTH Yard / Inch Meter / Centimeter MASS Ounce / Pound Gram / Kilogram VOLUME Quart Liter TEMPERATURE Fahrenheit Celsius / Kelvin TIME Second All Measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.
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In the English system you have to remember so many numbers . . .
12 inches in a foot 3 feet in a yard 5,280 feet in a mile 16 ounces in a pound 4 quarts to a gallon In the SI System you only have to remember one number. The SI System is based on the number 10.
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The SI System uses the following prefixes:
Kilo 1000 Hecto 100 Deca 10 UNIT 1 Deci 1/10 Centi 1/100 Milli 1/1000 This system works with any SI measurement. The UNIT becomes whichever type of measurement you are making. (mass, volume, or length) It is the same system regardless if you are measuring length, mass, or volume. You can remember the SI system with: King Henry Died Unexpectedly Drinking Chocolate Milk
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How does converting units work?
Unlike the English system converting in the SI System is very easy. For Example in the English system if you wanted to know how many inches in 2 miles what would you do? Take the number of miles (2). Multiply it by the number of feet in a mile (5,280). Multiply that by the number of inches in a foot (12). ANSWER: 126,720 inches in 2 miles
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The SI system is much easier.
For example in the metric system if you wanted to know how many centimeters were in 3 meters, what would you do? Find the unit you have (meters). Find the unit you are changing to (centimeters). Count the number of units in-between (2). Move the decimal point that many spaces, in the same direction you counted (right). 3 meters = 300 centimeters Kilo Hecto Deca UNIT Deci Centi Milli
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( ) ( ) ____ ______ How many kilometers is 15,000 decimeters? 10 dm
1 km X km = 15,000 dm 1.5 km =
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More Conversions . . . 2,321.0 millimeters to meters = 2.321 meters
521.0 grams to hectograms = hectograms 8.5 kiloliters to centiliters = 850,000 centiliters NOTE: The digits aren’t changing, the position of the decimal is. In the English system the whole number changes. Kilo Hecto Deca UNIT Deci Centi Milli
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Basic Types of Measurement
Length: measures distance between objects Volume: measures the amount of space something takes up Mass: measures the amount of matter in an object In SI the basic units are: Length is the meter Mass is the gram Volume is the liter (liquid) Temperature is Celsius
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Metric Measurement: Length
Length is the distance between two points. Does not matter if it is width, height, depth, etc. All are length measurements. The basic unit of length in the SI System is the meter. The meter is about the length of the English yard (3 feet). Area is a variation of a length measurement. Area is length x width. Expressed in units2 (m2, cm2, mm2 etc.)
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Metric Measurement: Mass
Mass is a measurement of the amount of matter in an object. Basic unit of mass is the gram. There are 454 grams in one pound. Weight and mass are related, but NOT the same. Weight is the pull of gravity on an object The greater the mass, the larger the pull of gravity.
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Metric Measurement: Volume
Volume is a measurement of the amount of space something takes up. The basic unit used for volume is the liter. This unit is used for the volumes of liquids. Volumes of solids are figured using this formula: (L)ength x (W)idth x (H)eight cm x cm x cm = cm3 Objects without a definite length, width or height (a rock for example), can use water displacement to determine volume NOTE: 1 ml = 1 cm3
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Practice problems Write 55 decimeters as meters
Convert 1.6 kilograms to grams Change 2800 millimoles to moles Change 6.1 amperes to miliamperes
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Section 3: Organizing Data
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Continuous Line Graph A graph in which points on the line between the plotted points also have meaning. Sometimes, this is a “best fit” graph where a straight line is drawn to fit the data points. Note that the independent variable is on the X axis, & the dependent is on the Y axis.
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Bar Graph Displays data by using bars of equal width on a grid. The bars may be vertical or horizontal. Bar graphs are used for comparisons.
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Circle Graph (Pie Chart)
Displays data using a circle divided into sectors. We use a circle graph (also called a pie chart) to show how data represent portions of one whole or one group. Notice that each sector is represented by %
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REALLY, REALLY SMALL NUMBERS.
SCIENTIFIC NOTATION A QUICK WAY TO WRITE REALLY, REALLY BIG OR REALLY, REALLY SMALL NUMBERS.
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Mathematicians are Lazy!!!
They decided that by using powers of 10, they can create short versions of long numbers.
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Rules for Scientific Notation
To be in proper scientific notation the number must be written with * a number between 1 and 10 * and multiplied by a power of ten 23 X 105 is not in proper scientific notation. Why?
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Soooo 137,000,000 can be rewritten as 1.37 X 108
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Using scientific notation, rewrite the following numbers.
Now You Try Using scientific notation, rewrite the following numbers. 347,000. 3.47 X 105 902,000,000. 9.02 X 108 61,400. 6.14 X 104
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Convert these: 1.23 X , X 106 6,806,000
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Try These 4,000 4 X X 103 2, X 106 6,123, ,000, X 108
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In the United States, 15,000,000 households use private wells for their water supply. Write this number in scientific notation. 1.5 X 107
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The U.S. has a total of X 107 acres of land reserved for state parks. Write this in standard form. 12,916,000 acres
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Why does a Negative Exponent give us a small number?
10000 = 10 x 10 x 10 x 10 = 104 = 10 x 10 x 10 = 103 = 10 x 10 = 102 = 101 1 = 100 Do you see a pattern?
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Sooooo = 10-1 = = 10-2 = = 10-3 = = 10-4
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Using Scientific Notation, rewrite the following numbers.
Your Turn Using Scientific Notation, rewrite the following numbers. 8.82 X 10-4 5.9 X 10-7 4 X 10-5
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More Examples 4 X 10-4 2) 1.248 X 10-6 .000001248 3) 6.123 X 10-5
1) 4 X 10-4 2) X 10-6 3) X 10-5 4) 3.06 X 10-6 5) 8.92 X 10-4
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.000007 The nucleus of a human cell is about
7 X 10-6 meters in diameter. What is the length in standard notation?
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A ribosome, another part of a cell, is about 0
A ribosome, another part of a cell, is about of a meter in diameter. Write the length in scientific notation. 3 X 10-9
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Significant Figures Scientist use significant figures to determine how precise a measurement is Significant digits in a measurement include all of the known digits plus one estimated digit Accuracy – Compares a measurement to the true value Precision – describes how closely measurements are to each other and how carefully measurements were made
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For example… Look at the ruler below Each line is 0.1cm
You can read that the arrow is on 13.3 cm However, using significant figures, you must estimate the next digit That would give you cm
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Let’s try this one Look at the ruler below
What can you read before you estimate? 12.8 cm Now estimate the next digit… 12.85 cm
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The same rules apply with all instruments
Read to the last digit that you know Estimate the final digit
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Let’s try graduated cylinders
Look at the graduated cylinder below What can you read with confidence? 56 ml Now estimate the last digit 56.0 ml
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One more graduated cylinder
Look at the cylinder below… What is the measurement? 53.5 ml
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Rules for Significant figures Rule #1
All non zero digits are ALWAYS significant How many significant digits are in the following numbers? 3 Significant Figures 5 Significant Digits 4 Significant Figures 274 25.632 8.987
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Rule #2 All zeros between significant digits are ALWAYS significant
How many significant digits are in the following numbers? 3 Significant Figures 5 Significant Digits 4 Significant Figures 504 60002 9.077
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Rule #3 All FINAL zeros to the right of the decimal ARE significant
How many significant digits are in the following numbers? 32.0 19.000 3 Significant Figures 5 Significant Digits 7 Significant Figures
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Rule #4 All zeros that act as place holders are NOT significant
Another way to say this is: zeros are only significant if they are between significant digits OR are the very final thing at the end of a decimal
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For example How many significant digits are in the following numbers? 1 Significant Digit 3 Significant Digits 6 Significant Digits 2 Significant Digits x
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Rule #5 All counting numbers and constants have an infinite number of significant digits For example: 1 hour = 60 minutes 12 inches = 1 foot 24 hours = 1 day
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How many significant digits are in the following numbers?
x 2 Significant Digits 6 Significant Digits 3 Significant Digits 4 Significant Digits 1 Significant Digit
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Rules Rounding Significant Digits Rule #1
If the digit to the immediate right of the last significant digit is less than 5, do not round up the last significant digit. For example, let’s say you have the number and you want 3 significant digits The last number that you want is the 8 – 43.82 The number to the right of the 8 is a 2 Therefore, you would not round up & the number would be 43.8
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Rounding Rule #2 If the digit to the immediate right of the last significant digit is greater that a 5, you round up the last significant figure Let’s say you have the number and you want 4 significant digits – The last number you want is the 8 and the number to the right is a 7 Therefore, you would round up & get 234.9
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Rounding Rule #3 If the number to the immediate right of the last significant is a 5, and that 5 is followed by a non zero digit, round up (you want 3 significant digits) The number you want is the 6 The 6 is followed by a 5 and the 5 is followed by a non zero number Therefore, you round up 78.7
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Rounding Rule #4 If the number to the immediate right of the last significant is a 5, and that 5 is followed by a zero, you look at the last significant digit and make it even. (want 3 significant digits) The number to the right of the digit you want is a 5 followed by a 0 Therefore you want the final digit to be even 2.54
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Say you have this number
(want 3 significant digits) The number to the right of the digit you want is a 5 followed by a 0 Therefore you want the final digit to be even and it already is 2.52
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Let’s try these examples…
(want 3 SF) (want 2 SF) (want 3 SF) (want 1 SF) (want 2 SF)
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Using Scientific Notation in Multiplication, Division, Addition, and Subtraction
Scientists must be able to use very large and very small numbers in mathematical calculations. As a student in this class, you will have to be able to multiply, divide, add and subtract numbers that are written in scientific notation. Here are the rules.
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Sample Problem: Multiply (3.2 x 10-3) (2.1 x 105)
Multiplication When multiplying numbers written in scientific notation…..multiply the first factors and add the exponents. Sample Problem: Multiply (3.2 x 10-3) (2.1 x 105) Solution: Multiply 3.2 x Add the exponents Answer: 6.7 x 102
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Sample Problem: Divide (6.4 x 106) by (1.7 x 102)
Division Divide the numerator by the denominator. Subtract the exponent in the denominator from the exponent in the numerator. Sample Problem: Divide (6.4 x 106) by (1.7 x 102) Solution: Divide 6.4 by Subtract the exponents 6 - 2 Answer: 3.8 x 104
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Addition and Subtraction
To add or subtract numbers written in scientific notation, you must….express them with the same power of ten. Sample Problem: Add (5.8 x 103) and (2.16 x 104) Solution: Since the two numbers are not expressed as the same power of ten, one of the numbers will have to be rewritten in the same power of ten as the other. 5.8 x 103 = .58 x so .58 x x 104 =? Answer: x 104
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Using Significant Figures in Mathematics
RULE 1. In carrying out a multiplication or division, the answer cannot have more significant figures than either of the original numbers.
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RULE 2. In carrying out an addition or subtraction, the answer cannot have more digits after the decimal point than either of the original numbers. Chapter Two
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Multiplication and division
32.27 1.54 = 3.68 = 1.750 = 3.2650106 = 107 6.0221023 1.66110-24 = 49.7 46.4 .05985 1.586 107 1.000
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Addition and Subtraction
.71 82000 .1 Look for the last important digit = .713 = = 10 – = __ ___ __
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