ICP

1. ICP The Nature of Science

2. How Science Takes Place • A scientist may perform experiments to find a new aspect of the natural world, to explain a known phenomenon, to check the results of other experiments, or to test the predictions of current theories.

3. How do scientists find answers? • Scientists answer questions by investigating. • Scientists plan experiments. • Scientists observe. • Scientists always confirm results.

4. The Branches of Science • Most of the time, natural science is divided into: • Biological science—the science of living things; ex: botany, zoology • Physical science—the science of matter and energy; ex: Physics and Chemistry • Earth science—the science of the earth; ex: geology, astronomy, meteorology

5. The Branches of Science Work Together • The branches of science are not totally separate but are mixed. • For example: living things (biology) are made of chemicals (chemistry) but may move (physical). • Likewise, geophysics—the study of the forces affecting earth, is both an Earth Science and a physical science.

6. What is a theory? • Scientific theory is developed from a hypothesis that has been tested and supported many times. • A theory must be able to explain observations clearly, be supported by repeated experimentation, and be able to make predictions about an experiment.

7. Theory VS Law • If a theory can ever be proven to be true, it becomes a scientific law or law of nature. • Theories explain why something happens, and laws describe how something works. • Example: Columbus had a theory that the earth was round. Today we know it is a true fact.

8. Theories and Laws are Tested • Sometimes theories must be changed or replaced when new discoveries are made. • More than 200 years ago, scientists used the caloric theory to explain how objects become warmer and cooler. • Heat was thought to be an invisible fluid (caloric), which flowed into or out of objects to change the temperature.

9. Theories and Laws are Tested cont. • The caloric theory couldn’t explain why rubbing your hands together produced heat. • Finally, in the 1800s, a new theory, the kinetic molecular theory, was able to explain how rubbing two surfaces together caused the atomic particles to move, producing thermal energy.

10. Models • A model is a representation of an object or event that can be studied to understand the real object or event. • Sometimes models are used to represent things that are too small or too large to be studied easily. • A model can be a mental ‘picture’ or a set of rules that describes how something works. • Meteorologists use models to predict weather.

11. Thinking Critically • Scientists must think critically to solve problems. • Critical thinking involves asking questions, making observations, and using logic to figure out a possible solution. • Galileo was the first scientist to define a set procedure to solve problems. • He is called the father of the scientific method.

12. Scientific Method • Scientific method begins with a question to be answered. • Research or make observations. • A hypothesis is formed which makes a prediction. • An experiment tests the hypothesis and is used to gather data. • Data is analyzed to reach a conclusion.

14. Testing Involves Variables • Scientists test a hypothesis by doing a controlled experiment. • Variables that can affect the outcome of the experiment are kept constant (controlled), except the one that you want to measure, • Only the results of the changing variable is observed.

15. Test One Variable at a Time • By testing one variable at a time, scientists are able to gather reliable data. • If an experiment does not give the expected results, you can test a different variable. • Always focus on the question to be tested in order to prevent bias in the experiment. • Peer review is important as a way to eliminate bias from scientific findings.

16. Tools of Scientists • Scientists use many tools to make observations and gather data. • Logical thinking and technology are tools. • All scientists use mathematics as one tool. • Math is the language of science, and mathematical models rely on accuracy. • The standard units of measure used by scientists is called the International System of Units, SI,

17. International System of Units • The International System of Units (SI) is used throughout the world. The National Institute of Standards and Technology keeps the official standards for the units of length, mass, and time for the United States. • Fundamental Units—The basic 3 SI units used to describe other quantities • Derived units—Combinations of the fundamental units

18. Fundamental Units • Length The base SI unit to measure length is the meter (m). • Mass The base SI unit to measure mass is the kilogram (kg). • Time The base SI unit to measure time is the second. • Volume The base SI unit to measure volume is the liter (L). a

19. Important SI Prefixes

20. Small to large Convert 1.85 m to cm 1.85 m X 100 cm/1m 1.85 X 100 cm 1 185 cm Large to small Write 265 km as m 265 km X 1000 m/1km 265 X1000 m 1 265,000 m Converting Units

21. Organizing Data • Graphs are important to show the relationship between variables in an experiment. • The independent variable (x) is the variable controlled by the experimenter. • The dependent variable (y) is called the responding variable because it changes every time x changes.

22. Bar graphs are used to compare data. Line graphs show continuous changes. Pie graphs show parts of a whole. Types of Graphs

23. Scientific Notation • Scientific Notation is based on exponential notation. It is used to express either very large or very small numbers in a shortened form. • Scientific notation makes working with these numbers much easier

24. Rules of Scientific Notation • The notation is based on powers of base number 10. The general format looks something like this: • N X 10x where N= number greater or equal to 1 but less than 10 and x=exponent of 10. • Ex: 5.2 X 107 m = 52,000,000 m

25. Practice Problems • Express the following measurements in scientific notation: • a. 5800 m b. 450,000 m • a. 0.000508 kg b. 0.00000045 kg c. 0.003600kg • a. 300,000,000 s b.186,000 s c. 93,000,000 s

26. Precision VS Accuracy • Precision is the exactness of a measurement. For ex: You measure something to be 1 inch but someone else measures it to be 1.1 inch. 1.1 is more exact. • Accuracy is a description of how close a measurement is to the true value of the quantity measured. You can only be as accurate as the measuring device used.

27. Rules for Significant Digits • Rules for determining which digits in a measurement are significant are: • Every nonzero digit in a recorded measurement is significant. • Zeroes appearing between nonzero digits are significant. The Zeroes in front of (before) all nonzero digits are merely placeholders; they are not significant. 0.0000099 only has two significant figures. • Zeroes at the end of the number if a decimal point is present and also zeroes to the right of the decimal are significant. The measurements 1241.20 m, 210.100 m and 5600.00 all have six significant digits. • Zeroes at the end of a measurement and to the left of an omitted decimal point are ambiguous. They are not significant if they are only place holders: 6,000,000 live in New York—the zeroes are just to represent the magnitude of how many people are in N.Y. But the zeroes can be significant if they are the result of precise measurements.

28. Practice Problems 1. State the number of significant digits in each measurement. • 2804 m b. 2.84 m c. 0.0029 m d. 0.003068 m e. 4.6 x 105 m f. 4.06 x 105 • 75 m h. 75.00 mm i. 0.007060 kg j. 1.87 x 106 ml k. 1.008 x 108 m l. 1.20 x 10-4 m

29. Answers • 1.a 4 b. 3 c. 2 d. 4 e. 2 f. 3 g. 2 h. 4 i. 4 j. 3 k. 4 l. 3