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Physical Science Unit 1: Introduction Chapter 1
What is Science • Science is a system of knowledge and the methods you use to find that knowledge. • Science begins with curiosityand often ends with discovery.
What is Science? • Generally scientists believe that the universe can be described by basic rules and these rules can be discovered by careful, methodical study.
Science vs. Technology Technology – the application of science Science and technology are interdependent. Advances in one lead to advances in the other
Branches of Science Chemistry: The study of Matter and its changes Physics: The study of Forces and Energy
What is the Scientific Method? • Scientific method refers to the techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge • It’s an organized plan for gathering, organizing, and communicating information. • Everyone can use the scientific method • The goal of any scientific method is to solve a problem or to better understand an observed event
How Science is conducted • Science is an investigation, which starts with observations leading to inferences. • An observation is any information collected with the senses. • An inference is conclusions or deductions based on observations.
Practice • Observations: • I hear people screaming • I smell cotton candy, popcorn, and hamburgers • I see a lot of people • Inference = ?
Basic steps of scientific method • Make an observation • Ask a question • Form a hypothesis • Test hypothesis • Analyze data/draw conclusion • Develop theory
Scientific Method Steps 1-3 • Begins with an observation (ex. I see smoke in the distance) 2. that leads to a question. (ex. what’s causing the smoke) 3. Form a hypothesis – a possible answer that you can test. (ex. Some one is burning leaves.)
Scientific Method Step 4 • A good experiment tests only one variable at a time. • No experiment is a failure. Conduct an Experiment
Variables Variable – anything that can change in an experiment • Independent variable – what you change. (manipulated) • Dependent variable – what changes because of the independent variable. (responding) • Control-what you keep the same
Qualitative vs Quantitative • Qualitative – describes with words. • Quantitative – describe with measurements
Scientific Method Step 5 • Data DOES NOT support hypothesis then you need to revise the hypothesis and retest • Data supports hypothesis than additional testing is needed before developing a theory Analyze data
Scientific Method Step 6 • Is an explanation that has been tested by repeated observations. • Are always being questioned and examined. • To be valid, a theory must continue to pass each test. Scientific Theory
Scientific Theory (cont.) • A theory must explain observations simply and clearly. • Experiments that illustrate the theory must be repeatable. • You must be able to predict from the theory
Scientific Method Step 6 cont • States a repeated observation about nature. • Does not explain why an event happens. Scientific Law
Theories and Laws are not absolute • Sometimes theories or Laws have to be changed or replaced completely when new discoveries are made.
Scientific Model • Model is an representation of an object or event. • Scientific models make it easier to understand things that might be too difficult to observe directly
Graphs • A way of organizing and presenting data. • Makes relationships more evident.
Line graphs • Best for displaying data that change. (anything over time) • Numerical vs. Numerical.
Multiple Line Graphs • Best for comparing multiple values and distributions
Bar Graphs • Best when comparing data for several individual items or events. • Numerical vs. non-numerical
Circle Graphs (pie charts) • Best for displaying data that are parts of a whole.
Scientific Notation • When writing very large or very small numbers, scientists use a kind of shorthand called scientific notation. • This is a way of writing a number without so many zeros.
Examples: • The speed of light is about 300,000,000 m/s • Or 3.0 x 108 • The mass of a proton is 0.000000000000000000000001673 • Or 1.673 X 10-24
All you do is move the decimal • 850,000,000.0 8 5 0 0 0 0 0 0 0 . 0 = 8.5 x 108 • 0.000,000,025 0 . 0 0 0 0 0 0 0 2 5 = 2.5 x 10-8 + -
Scientific Notation Examples • 3.256 x 104 • 9.78 x 109 • 5.24 x 10-3 • 2.41 x 10-7
Scientific Notation Examples • 0.007899 = ? • 898745.30 = ? • 0.00003657= ? • 531120 = ?
Units of Measurement • Scientists use the International System of Units (SI units) for measurements. • When everyone uses the same units, sharing data and results is easier – less mistakes.
Base Units • The official SI units to measure: • Length = meter (m) • Volume = liter (L) • Mass = gram (g) • Time = seconds (s) • Temperature = Kelvin (K)
Derived Unit • derived units, are made from combinations of base units. • Area: square meter (m2) • Volume: cubic meter (m3) • Density: kilograms per cubic meter (kg/m3) [a measurement of mass/area] • Pressure: pascal (Pa) [a measurement of force/area] • Energy: Hertz (Hz) [a measurement of force/distance] • Electric charge: coulomb (C) [is a measurement of current /time]
Metric Prefixes Metric prefixes allow for more convenient ways to express SI base and derived units.
King Henry - Conversions • Use the sentence “King Henry Died by Drinking Chocolate Milk.” to remember the order of prefixes. Kilo HectoDekabaseDeciCentiMilli meter liter gram
Limits of Measurement • Precision is a gauge of how exact a measurement is. • Precise measurements are close to each other • Accuracy is the closeness of a measurement to the actual value of what is being measured • An accurate measure is close to the true or expected value