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The Scientific Method “A Way to Solve a Problem”

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What is the Scientific Method? It is the steps someone takes to identify a question, develop a hypothesis, design and carry out steps or procedures to test the hypothesis, and document observations and findings to share with someone else. In other words, it’s a way to solve a problem. The Scientific MethodThe Scientific Method (Lyrical Life Science) audio clip

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Scientist have to take the time to think logically when they are investigating a question or problem. Scientists develop a question, gather information and form an hypothesis. The next step scientists take is to create and conduct an experiment to test their hypothesis.

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A key to experiments is observing what happens and writing it down. Gathering information or data and documenting it so it is readable and makes sense to others is really important.

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Once a scientist completes an experiment, they often repeat it to see if they get the same findings and results. This is really what we call verification, or checking things out to make sure everything was valid and will happen again and again.

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Scientists share their experiments and findings with others. Because they share their experiments and findings, scientists can learn from each other and often use someone else’s experiences to help them with what they are studying or doing.

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The steps of the Scientific Method are: Question/Problem Research (sometimes omitted) Hypothesis Procedure/Method Data Observations Conclusion

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Measurement & Scientific Notation A discussion of the how’s and why’s

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Reliability of Measurement: *Accuracy - Refers to how close a measurement is to the true value of the quantity. *Precision - Refers to how close a set of measurements for a quantity are to one another, regardless of whether they are correct.

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o Measuring is an important skill. It is especially important in science. In order for measurement to be useful, a measurement standard must be used. o A standard is an exact quantity that people agree to use for comparison.

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o When all measurements are made using the same standard, the measurements can be compared to each other. o In 1960, the International System of Units, is devised. SI is the standard system of measurement used worldwide. All SI standards are universally accepted and understood by scientists.

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o In SI (MKS), each type of measurement has a base unit, such as the meter, which is the base unit for length. o Other base units are the gram (mass), Kelvin (temperature), and second (time). oThe system is easy to use because it is based on multiples of ten.

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oPrefixes are used with the names of the base units to indicate what multiple of ten should be used wit the base unit. For example, the prefix kilo- means 1000. So a kilometer is 1000 meters.

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KiloHectoDecaBasic Unit DeciCentimilli (k)(h)(da)Gram (g) (d)(c)(m) 100010010Liter (L) 0.10.010.001 10 3 10 2 10 1 Meter (m) 10 -1 10 -2 10 -3 Move decimal RIGHT when going from big unit to small Move decimal to LEFT when going from small unit to big

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MEASUREMENT DETERMINE THE CONVERSION 1. 123 Km = 123,000 meters 2. 145 mL = 14.5 cL 3. 34 cm = 0.00034 Km 4. 75 dg = 7.5 g 5. 23 Km = 2,300,000 cm http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

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Percent of Error - The comparison of an experimental value to a known value. We will use this calculation to determine how well you did your experimental measurements.

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D = M/V => 0.304 g/cm 3 M = DV => 426.4 g V = M/D => 39.68 cm 3

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Cube 5.4 g 2 cm 3 Density = 2.7 g/cm 3 Rectangle 34.2 g 12 cm 3 Density = 2.7 g/cm 3 Sphere 2.9 g 1.1 cm 3 Density = 2.6 g/cm 3 (glass) Sphere 8.6 g 1.1 cm 3 Density = 7.8 g/cm 3 (steel)

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Scientific Notation Science deals with very large and very small numbers. Consider this calculation: (0.000000000000000000000000000000663 x 30,000,000,000) ÷ 0.00000009116 Hopefully you can see, how awkward it is. Try keeping track of all those zeros! In scientific notation, this problem is: (6.63 x 10 ¯31 x 3.0 x 10 10 ) ÷ 9.116 x 10 -8 It is now much more compact, it better represents significant figures, and it is easier to manipulate mathematically.

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The trade-off, of course, is that you have to be able to read scientific notation. This lesson shows you (1) how to write numbers in scientific notation and (2) how to convert to and from scientific notation. Keep in mind that a number like 9.116 x 10 -8 is ONE number (0.00000009116) represented as a number 9.116 and an exponent (10 -8 ).

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Format for Scientific Notation 1. Used to represent positive numbers only. 2. Every positive number X can be written as: (1 < N < 10) x 10 some positive or negative integer Where N represents the numerals of X with the decimal point after the first nonzero digit.

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3. A decimal point is in standard position if it is behind the first non-zero digit. Let X be any number and let N be that number with the decimal point moved to standard position. Then: *If 0 < X < 1 then X = N x 10 negative number *If 1 < X < 10 then X = N x 10 0 *If X > 10 then X = N x 10 positive number

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Example #1 - Convert 29,190,000,000 to scientific notation. The answer will be four significant figures. Explanation Step 1 - start at the decimal point of the original number and count the number of decimal places you move, stopping to the right of the first non-zero digit. Remember that's the first non-zero digit counting from the left.

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The answer is 2.919 x 10 10. Step 2 - The number of places you moved (10 in this example) will be the exponent. If you moved to the left, it's a positive value. If you moved to the right, it's negative.

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Example 2 - Write 0.00000000459 in scientific notation. Step 2 - Now count how many decimal places you would move from 4.59 to recover the original number of 0.00000000459. Step 1 - Write the digits down with the decimal point just to the right of the first digit. Like this: 4.59. Please be aware that this process should ALWAYS be between 1 &10.

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The correct answer is: 4.59 x 10 ¯9 Step 3 - Write 4.59 times the other number, BUT, write the other number as a power of 10. The number of decimal places you counted gives the power of ten. In this example, that power would be 9. The answer in this case would be 9 places to the LEFT. That is the number 0.000000001. Be aware that this number in exponential notation is 10 ¯9.

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Some examples: * 250,000,000,000 becomes 2.50 x 10 11 * 4.56 becomes 4.56 x 10 0 * 0.000000809 becomes 8.09 x 10 -7 * 23,000,000 becomes 2.3 x 10 7 * 9.8becomes 9.8 x 10 0 (the 10 0 is seldom written) * 0.00087becomes 8.7 x 10 ¯4

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PART 2 - SCI NOTATION 1.1230000 = 2. 0.00023 = 3. 21530 = 4. 3.1 x 10 4 = 5. 2.3 x 10 - 5 = 6. 2.7 x 10 - 3 + 3.1 x 10 -4 = 7. 3.3 x 10 5 ÷ 8.9 x 10 4 = 1.23 x 10 6 2.3 x 10 -4 2.153 x 10 4 31000 0.000023 3.01x 10 -3 3.7 x 10 0

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Significant Digits and Measurements Properties of Matter are either: *Qualitative - Described without measurements. *Quantitative - Measured and described by a number of standard units. X

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Significant Digits: *A significant digit is one which is actually measured. *The number of significant digits in a measurement depends on the ability of the measuring device. * When a calculation involves measurements with different numbers of significant digits, the answer should have the same number of significant digits as the least in the measurements.

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Rules for Assigning Significance to a Digit: *Digits other than zero are always significant. *Final zeros after a decimal point are always significant. *Zeros between two other significant digits are always significant. *Zeros used only to space the decimal are never significant.

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How many significant digits do the following numbers indicate: 0.00004506000 23.056 7.2000 X 10 9 0.00001 2.304 X 10-3 7 significant digits 5 significant digits 1 significant digit 4 significant digits

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