The Nature of Science

1. The Nature of Science

2. The Methods of Science What is science? 1. A method for studying the natural world 2. From Latin word scientiawhich means “knowledge” 3. Follows rules or natural patterns

3. Major Categories of Science • Earth and Space Science (geology, meteorology, astronomy, etc.) • Life Science (genetics, botany, ecology, zoology, etc.) • Physical Science (matter & energy) The sciences often overlap

4. Science Explains Nature Explanations are modified as we learn more about the natural world often through new technology

5. Pure Science vs. Technology Pure science – scientists who do experiments to learn more about the natural world. Technology – the application of science for practical uses; can be controversial (i.e., genetic engineering, stem cell research)

6. Scientific Theories and Laws Theory – must be able to explain observations clearly and consistently (based on knowledge gained from many observations); not a guess; experiments that illustrate the theory must be repeatable with the same result; must be able to predict results from the theory. Law- astatement about what happens in nature and seems to be true every time; predicts what will happen in a given set of conditions, but does not explain how or why A theory can explain a law.

7. Scientific Method- An organized set of investigation procedures which includes: • Stating a Problem • Researching & Gathering Information • Forming a hypothesis (a testable prediction) • Testing a hypothesis includes: • making observations • building or using a model • performing an experiment • Designing a controlled experiment with multiple trials • Gathering Data • Analyzing Data • Drawing Conclusions • Being Objective (eliminating bias)

8. Variable - a quantity that can have more than one value. a. Independent Variable b. Dependent Variable c. Constants d. Control

9. Variable - a quantity that can have more than one value. a. Independent Variable - “you change it” b. Dependent Variable – “it changed” c. Constants – all of the things that remain the same d. Control – a standard for comparison

10. Making Observations • Qualitative observations – using the 5 senses • Quantitative observations – making measurements

11. Discover how long a foot is: 1. Measure the distance across your classroom using your foot as a measuring device. 2. Record your measurement and name your measuring unit. 3. Repeat steps 1 and 2 for each group member.

12. Discover how long a foot is: 1. Measure the distance across your classroom using your foot as a measuring device. 2. Record your measurement and name your measuring unit. 3. Repeat steps 1 and 2 for each group member.

13. Units of Measurement A. Units and Standards 1. Standard - an exact quantity that people agree upon using for measurement 2. Cannot compare measurements without a standard 3. A measurement consists of a number and a unit.

14. Measurement Systems 1. English System – (feet, yards, inches, miles, pounds, etc.) 2. Metric system – based on multiples of 10; devised by a group of scientists in the late 1700s.

15. International System of Units (SI) SI Units are used for consistency a. improved version of metric system in 1960s b. universally used and accepted by scientists world-wide c. Each type of measurement has a prefix & base unit (meter, Liter, gram)

16. 4. SI Prefixes Kilo – Hecto- Deka – Basic Unit deci- centi- milli- (k) (H) (D) (m, L, g, s) (d) (c) (m) 103 102 101 100 10-1 10-2 10-3

17. 5. SI Standards of Measurement

18. Measure the length and width of an index card using the least precise to the most precise measuring device. Data

19. 7.

20. 6. Significant Figures All of the numbers in a measurement known for certain plus an estimated digit. (See Handout)

21. All digits 1-9 are significant. • Example: 129 has 3 significant digits • 2. Zeros between significant digits are always significant. • Example: 5007 has 4 significant digits • 3. Trailing zeros in a number are significant only if the number contains a decimal point. • Examples: 100.0 has 4 significant digits • 100. has 3 significant digit • 100 has 1 significant digit

22. 4. Zeros in the beginning of a number whose only function is to place the decimal point are not significant. Example: 0.0025 has 2 significant digits 0.004 has 1 significant digit 5. Zeros following a decimal significant digit are significant. Example: 0.000470 has 3 significant digits 0.47000 has 5 significant digits

23. ATLANTIC-PACIFIC RULE If the decimal is ABSENT, start with the first non-zero number on the ATLANTIC side and count going LEFT. If the decimal is PRESENT, start with the first non-zero number on the PACIFIC side and count going RIGHT.

24. Precision vs. Accuracy

29. Scientific Notation

30. How to write a very large number, such as 46,350,000 = 4.635 x 107 coefficient Move the decimal until you get to a number 1- 9.9 The number of times moved is equal to the exponent.

31. When the number is less than one, the exponent will be negative. 0.000224 = 2.24 x 10-4

32. Scientific Notation Practice • 425 cm = • 36000 cg = • 0.00098 m = • 0.0135 kg = • 1000.345 g =

33. Scientific Notation Answers • 425 cm = 4.25 x 102 cm • 36000 cg = 3.6 x 104 cg • 0.00098 m = 9.8 x 10-4 m • 0.0135 kg= 1.35 x 10-2 kg • 1000.345 g = 1.000345 x 103 g

34. Calculations with Scientific Notation

35. When adding or subtracting numbers in scientific notation, the power of 10 must be the same. Example: 3.6 x 103 + 5.2 x 102 = 3.6 x 103 + 0.52 x 103 = 4.1 x 103 OR 36 x 102 + 5.2 x 102 = 41.2 x 102 =4.1 x 103

36. When multiplying numbers in scientific notation, multiply the coefficients, then ADD exponents. Examples: 1. (3 x 102 )(2 x 105) = 6 x 107 2. (4 x 104 )(5 x 105) = 20. x 109 = 2 x 101 x 109 = 2 x 1010

37. When dividing numbers in scientific notation, divide the coefficients, then SUBTRACT exponents. Examples 1)4 x 103 = 2 x 103-2 = 2 x 101 2 x 102 2)4 x 10-3 = 2 x 10 -3- -2 = -3 +2 = 2 x 10 -1 2 x 10-2

38. Dimensional Analysis

39. How many seconds are in one year?

40. 8. Converting Between SI Units Dimensional Analysis is a method of problem-solving that focuses on the units used to describe matter.

41. 9. Dimensional Analysis A conversion factor -a ratio of equivalent values Example, 1 dozen = 12 eggs could be written: 1 dozen or 12 eggs 12 eggs 1 dozen

42. Examples: 1) 30 eggs = ______ dozen 30 eggs x 1 dozen = 2.5 dozen 12 eggs

43. 2) 1.5 dozen = ______ eggs 1.5 dozen x 12 eggs = 18 eggs 1 dozen

44. 3) If you buy 13.3 gallons of gasoline at $2.899/gallon, how much do you pay? 13.3 gal x $2.899 = $ 38.56 1 gal (if it had been $2.89/gallon, it would be $38.44)

45. Kilo – Hecto- Deka – Basic Unit deci- centi- milli- 4) 1.225 L = ________ mL 1 L = 1000 mL 1.225 L x 1000 mL = 1225 mL 1 L

46. 5) 5400 mg = ______ g 1000 mg = 1 g 5400 mg x __1 g__ = 5.4 g 1000 mg Kilo – Hecto- Deka – Basic Unit deci- centi- milli-

47. Measuring Distance 1. Length is the distance between 2 points. 2. Choosing a Unit of Length a. unit chosen depends on the size of the object.

48. Measuring Volume 1. Volume – the amount of space occupied by an object 2. Volume formulas: Rectangular Solids: V = lwh Cylinder: V = πr2h Sphere: V = 4 πr3 3

49. Measuring Liquid Volume a. Usually expressed in Liters (L) or milliliters (mL) b. 1 cc = 1 cm3 = 1 mL

50. Converting from Liters to cm3 1.5 L x 1000 mL x 1 cm3 = 1500 cm3 1 L 1 mL