Understanding Science: Methods, Measurement, and the Metric System

1. What is Science • Study of the physical universe • An organized body of facts • Experimentation • Observation • Cannot be vague • Avoid inference

2. Scientific Method – is a problem solving process • Define the problem – ask a question • Form a hypothesis – educated guess • Test the hypothesis – use the tools of science • Accept or reject hypothesis – evaluate data • Reformulate hypothesis • Verify hypothesis - retest

3. Measurement in Science • Scientific Notation – a shorthand method for writing very large and small numbers • Metric System – an international measurement system that uses the decimal system units of division (base 10) • Significant Figures – any measurement which is reliable

4. Scientific Notation • Numbers are expressed as a value between 1 and 10 (not 10) times 10 raised to a power • Ex. 2.15 x 10 -7 = 0.000000215 ● Addition and Subtraction – exponents must have the same value ● Multiplication – add exponents ● Division – subtract exponents

5. Addition and Subtraction 7.55 x 10 -7 +2.45 x 10 -5 Must change exponents to match 7.55 x 10 -7 + 245. x 10 -7 Note: the exponent got 252.55 x 10 -7 smaller so the number gets bigger Final correct ans. 2.5255 x 10 -5 Subtraction follows the same rule

6. Multiplication – add exponents 5.39 x 10 5 x 3.21 x 10 3 17.30 x 10 8 Note: the answer is not in proper scientific notation 1.73 x 10 9 Proper Scientific Notation

7. Division – subtract exponents 7.26 x 10 5÷ 3.21 x 10 3 = 226 Note: the answer is not in proper scientific notation 2.26 x 10 2 Proper Scientific Notation 2.08 x 10 -6 = 0.648 x 10 -1 3.21 x 10 -5 Note: the answer is not in proper scientific notation 6.48 x 10 -2Proper Scientific Notation

8. Metric System • Basic Units • Meter – length • Gram – mass • Cubic decimeter (or Liter) – volume • Kelvin (or Celsius) – temperature • Seconds – time • Joules – energy

9. Metric System Prefixes • kilo - 103 - 1000 times basic unit • hecto - 102 - 100 times basic unit • deka – 101 – 10 times basic unit • deci - 10-1 - 0.1 times basic unit • centi -10-2 - 0.01 times basic unit • milli - 10-3 - 0.001 times basic unit • micro - 10-6 - 0.000001 times basic unit Metric converter - is helpful when learning conversions

10. Metric Converter Smaller Prefix Factor Scientific Notation units nano (n) 1/1,000,000,000 10 -9 micro (m) 1/1,000,000 10 -6 milli (m) 1/1000 10 -3 centi (c) 1/100 10 -2 deci (d) 1/10 10 -1 Standard (Meter, Liter, 1 10 0 unit Gram) deka (D) 10 10 1 hecto (h) 100 10 2 kilo (k) 1000 10 3mega (M) 1,000,000 10 6giga (G) 1,000,000,000 10 9 Larger Units Decimal Point Movement

11. Significant Figures (digits) • Accuracy – difference between a measured value and the true or accepted value • Precision – degree of agreement between measured values

12. Accuracy vs. Precision Accurate Precise Accurate and Precise Note: The accurate target is not precise but the average of the values is accurate

13. Significant Figures • Rules for defining significant figures - Leading zeros are not significant Ex: 0.000025 • Trailing zeros are not significant unless there is a decimal point following them Ex: 2500000

14. Significant Figures (cont.) • Captive zeros are always significant Ex: 2003, 70.005, 0.0090006 • Zeros to the right of a decimal and a non-zero number are always significant Ex: 0.3500, 0.0000770, 90.000

15. Significant Figures • Rules of Operations • Addition and subtraction – the limiting term is the one with the smallest number of places to the right 6.345 1.00945 +0.125045- 0.210 6.470 0.799

16. Significant Figures • Rules of Operation (cont.) • Multiplication and division – the answer contains the same number of significant figures as the value with the smallest number of significant figures 9.110 0.4521= 0.374 x 0.025 1.21 0.23 Ans: 2 sig. figs. Ans: 3 sig. figs