Astronomy

1. Intoduction Astronomy NASA, ESA, S. Wyithe (University of Melbourne), H. Yan (Ohio State University), R. Windhorst (Arizona State University), and S. Mao (Jodrell Bank Center for Astrophysics, and National Astronomical Observatories of China)

2. Science, Matter, Energy and Systems Endeavor to discover how nature works and to use that knowledge to make predictions about what is likely to happen in nature.

3. Science • Science is a discipline that attempts to describe the natural world in terms of order. • Biology • Chemistry • Physics • Earth Science

4. Inference To conclude from evidence or premises To reason from circumstance; surmise: We can infer that his motive in publishing the diary was less than honorable To lead to as a consequence or conclusion: “Socrates argued that a statue inferred the existence of a sculptor”

5. Scientific method HYPOTHESIS – proposed to explain observed patterns Critical experiments Analysis and conclusions

6. Scientific Methods What is the question to be answered? What relevant facts and data are known? What new data should be collected? After collection, can it be used to make a law? What hypothesis can be invented to explain this? How can it become a theory?

7. Theory and Law Scientific Theory A hypothesis that has been supported by multiple scientists’ experiments in multiple locations A Scientific Law a description of what we find happening in nature over and over again in a certain way

8. Scientific Laws Law of Conservation of Matter Matter can be changed from one form to another, but never created or destroyed. Atomic Theory of Matter All matter is made of atoms which cannot be destroyed, created, or subdivided.

9. Reasoning Inductive Reasoning Uses observations and facts to arrive at hypotheses All mammals breathe oxygen. Deductive Reasoning Uses logic to arrive at a specific conclusion based on a generalization All birds have feathers, Eagles are birds, therefore All eagles have feathers.

10. Frontier and Consensus Science Frontier Science Scientific “breakthroughs” and controversial data that has not been widely tested or accepted String Theory Consensus or Applied Science Consists of data, theories, and laws that are widely accepted by scientists considered experts in the field involved Human Genome Project

11. Models • Scientists use models to imitate the system. • Mice are used to determine LD50 • Chemists use structural models when investigating a chemical • Remember the plum pudding! • Mathematical and computer models are able to predict many outcomes

12. Models have Factors • Factors represent the variables in a scientific theory • The factors that are involved in a theory about why you are late to my class • your walking speed • interference by your peers • the distance from point A to my room

13. A Good Scientist . . . • Always makes observations. • Always questions. • Always using good scientific practices to record and analyze data. • Repeats trials • Uses statistics to analyze data • Uses safe and accepted practices • Uses data to support hypotheses

14. Experiments Variables are what affect processes in the experiment. Controlled experiments have only one variable Experimental group gets the variable Control group does not have the variable Placebo is a harmless pill that resembles the pill being tested. In double blind experiments, neither the patient nor the doctors know who is the control or experiment group.

15. Variables • A variable is a source or variance in an experiment and include independent and dependent variables. • Independent variable (x-axis): the variable which is changed in an experiment. • Dependent variable (y-axis): the variable which is measured in an experiment.

16. A review and practice MEASURING AND CONVERSIONS

17. Qualitative or Quantitative? • Qualitative data describes the physical properties of matter in terms of a description, not a measurement. • Ex. Red ball, blue balloon • Quantitative data describes the physical properties of matter in terms of a measured or counted quantity • Ex. 25 eggs, 35.2 grams

18. Measuring • Measurement is determining the size or magnitude of something using a device or accepted value. All measurements have • magnitude, • Units, and • Uncertainty

19. Counting Numbers • Counting is never uncertain unless you estimate a very large number- counting is not a measurement • Exact numbers are obtained by counting or definition

20. Measurement Devices • devices have a limit on precision • zero a balance or correct for a measuring device • significant digits are part of a valid measurement depending on the divisions

21. Uncertainty? • All measurements have a certain degree of uncertainty, because of instrument calibration and human bias. • Measurements should be made recording all certain digits plus one estimated digit.

22. Reading a Volume • Always read the volume of a liquid at the bottom of the meniscus 50 40 30 20 10

23. Error • Errors in chemistry are classified as systematic (determinate) and random (indeterminate). • Error - the result of a measurement minus a true value of the measure and (physical paramater being quantified by measurement) • Systematic Error – an error that can be identified and is repeated • Random Error – an error that occurs due to irreproducible conditions.

24. Precision & Accuracy • accuracy is how well a measurement agrees with the true value • poor accuracy means poor equipment or flaw in procedures • relates to a chemical measure, qualitative concept • The error of an observation is the difference between the observation and the actual or true value of the quantity observed.

25. Precision • precision is how well a measuring device can reproduce a measurement • The term precision is used in describing the agreement of a set of results among themselves. Precision is usually expressed in terms of the deviation of a set of results from the arithmetic mean of the set • devices have a limit on precision; precise measurements that are not accurate indicate an equipment error; zero a balance or correct for a measuring device • poor precision means poor technique

26. Percentage Error • Percentage error is used to determine how far from the true value • Take the absolute value of the difference in the accepted value and the experimental value divided by the accepted or true value • Put the number into % form; Low % error indicates accuracy • % Error = 100 – percent correct • Percent correct = number correct / total

27. Scientific Notation

28. Scientific Notation • Scientific Notation is a way to express very large or very small numbers. • Scientific notation expresses numbers as a multiple of two factors: a number between 1 and 9; and ten raised to a power, or exponent. • The exponent is the magnitude of the number of places you move the decimal. • When you decrease the exponent, you move the decimal to the left; increase moves to the right.

29. Convert the following to scientific notation and then count the significant figures: • 1,392,000 g • 0.000 000 028 km • 0.000 000 000 000 050 ms • 472,920,000,000,000,000 mmol

30. Calculations • Multiplication: add the exponents • (5.0 x 103) x (2.0 x 102) • Division: subtract the exponents • (6.0 x 103) ÷ (2.0 x 102) • Addition/Subtraction: exponents must be the same before you perform the function • (1.50 x 102) + (3.45 x 103)

31. Metric Prefixes • Mega 1,000,000 • Kilo 1,000 • Hecto 100 • Deka 10 • Base 1 • Deci 0.1 • Centi 0.01 • Milli 0.001 • Micro 0.000 001 • Nano 0.000 000 001 • Pico 0.000 000 000 001 There is a factor of 1,000 between these two prefixes Each new unit is a factor of 1,000 less from this point on

32. What is what? • 1 million = 1 x 106 • 1 billion = 1 x 109 • 1 trillion = 1 x 1012

33. Percentages • A percentage is a ratio of 100 • 5% is 0.05 x 100 • What is 3.5% of 1,999,220? • What percentage of animals is 255 out of 3420?

34. It’s all Greek to me! • The Greek alphabet is still used today to represent quantities and constants in physics, chemistry, economics, statistics . . .

35. Using the measuring tools Measurements in the Laboratory

36. Temperature Conversions • In Chemistry, the temperature scale utilized is the Kelvin Scale • K = C + 273.15 • So, 100oC = 373 K • Fahrenheit and Celsius Conversions • oC = (oF – 32) x 5/9 • oF = (oC x 9/5 ) + 32

37. Calculating Volume • Of a rectangular prism or cube may be calculated by using the following formula: v=lwh • Of a cylinder may be calculated using the following formula: • Of a cone may be calculated using the following formula: • Of odd shaped objects: may be measured by the amount of water displaced when the objected is added to it

38. Displacement Method • In order to measure the volume of an irregular object, use the displacement method. • 1: using a graduated cylinder, measure and record the volume of water. • 2: place the object in the graduated cylinder so that it is completely submerged, but the water doesn’t overflow • 3: measure and record the new volume of water. • 4: subtract the initial volume from the final volume. This is the volume of the object in mL • 1 mL = 1 cm3

39. Density • Density is a derived unit that describes the ratio between both the mass and volume of matter. • D = m / v • What is the density of an object with a mass of 85.6 g and a volume of 17.99 mL? The density of tin is 7.265 g/mL. If a sample of tin has a mass of 13.6 g what is its volume?

40. Dimensional Analysis • A useful tool to solve many problems u • known x conversion factor = answer • Conversion factors are equivalents like • 1 dozen eggs = 12 each eggs • It is set up with the unknown number with unit divided by the known number with unit • If you have 2.35 kg of a sample whose density is 1.25 g/mL, how many Liters of sample do you have?

41. Putting it all together • Astronomical Units (AU): based on Earth’s average distance from the Sun. Used only for objects and distances within our solar system. • 1 AU = 149,597,871 km • Light Year (ly): the distance light travels in one Earth year • 1 ly = 9.461 x 1012 km • So how long does it take for light to reach the earth in years? How about days? Now hours? What about minutes?

42. Graphing Techniques

43. 1. Assign Variables To The Proper Axis A graph relates two variables from an experiment. One of the variables is changed in order to study how it affects the other variable. The variable that is manipulated by the experimenter is called the independent variable and it’s values are plotted on the ‘x’ or horizontal axis. The variable whose values are determined by the results of the experiment is called the dependent variable and is plotted on the ‘y’ or vertical axis.

44. 2. Set-up the scales Each axis must have a numbered scale to show the values of each variable. The scale should begin with a number slightly less than the lowest value and extend to a number slightly more than the greatest value and designed to occupy the majority of the paper. The scale must be uniform. That is each block on the graph must represent the same amount as any other block of that scale. Scales do not necessarily need to begin at zero. The two scales do not necessarily need to match.

45. 3. Label Each Axis Each axis must have a label which states the variable which is plotted on the axis. Each axis must indicate the unit used to measure the variable.

46. 4. Plot And Circle The Points Use a small uniform dot to plot each point in it’s proper position. A small circle is drawn around each dot. The purpose of the circle is to represent the uncertainty in the measurements of that set of data. In more advanced classes you may be asked to calculate the uncertainty of the measurements and to draw a circle that precisely represents that uncertainty.

47. 5. Connect The Points The points on the graph should be neatly connected to show the trend in the data. How the points are connected depends upon what kind of data was collected. Discrete data (counted items) are connected point-to-point by straight lines. Continuous data (measured quantities) are connected by a smooth line which may be straight or curved. The line does not need to touch each circle as it only shows the trend in the data.

48. 6. Title The Graph Each graph should have a title placed in some clear area, usually near the top of the paper. The title should be informative. That means that it should relate to the reader information about the experiment that is not part of the graph without the title.

49. The Experiment Various amounts of table salt are added to water and the boiling point of the solution is measured with a thermometer.

50. The Data Grams of NaClBoiling Point 0g 100.0oC 2g 103.1oC 4g 107.0oC 6g 107.9oC 8g 108.7oC 10g 109.5oC