1. Devil physics The baddest class on campus IB Physics

2. All You Need To Know About Physics

3. Lsn 1-3: Mathematical and Graphical Techniques

4. Questions From Reading Activity?

5. Essential Idea
Scientists aim towards designing experiments that can give a “true value” from their measurements, but due to the limited precision in measuring devices, they often quote their results with some form of uncertainty.

6. Nature Of Science
Uncertainties: “All scientific knowledge is uncertain… if you have made up your mind already, you might not solve it. When the scientist tells you he does not know the answer, he is an ignorant man. When he tells you he has a hunch about how it is going to work, he is uncertain about it. When he is pretty sure of how it is going to work, and he tells you, ‘This is the way it’s going to work, I’ll bet,’ he still is in some doubt. And it is of paramount importance, in order to make progress, that we recognize this ignorance and this doubt. Because we have the doubt, we then propose looking in new directions for new ideas.” (3.4) -- Feynman, Richard P The Meaning of It All: Thoughts of a Citizen-Scientist. Reading, Massachusetts, USA. Perseus. P 13.

7. Theory Of Knowledge
“One aim of the physical sciences has been to give an exact picture of the material world. One achievement of physics in the twentieth century has been to prove that this aim is unattainable.” – Jacob Bronowski.
Can scientists ever be truly certain of their discoveries?

8. Understandings Random and systematic errors
Absolute, fractional and percentage uncertainties
Error bars
Uncertainty of gradient and intercepts

9. Applications And Skills
Explaining how random and systematic errors can be identified and reduced
Collecting data that include absolute and/or fractional uncertainties and stating these as an uncertainty range (expressed as: best estimate ± uncertainty range)
Propagating uncertainties through calculations involving addition, subtraction, multiplication, division and raising to a power
Determining the uncertainty in gradients and intercepts

10. Guidance
Analysis of uncertainties will not be expected for trigonometric or logarithmic functions in examinations

11. Data Booklet ReferenceIf
Then
then

12. Utilization
Students studying more than one group 4 subject will be able to use these skills across all subjects

13. Aims
Aim 4: it is important that students see scientific errors and uncertainties not only as the range of possible answers but as an integral part of the scientific process
Aim 9: the process of using uncertainties in classical physics can be compared to the view of uncertainties in modern (and particularly quantum) physics

14. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?

15. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?
Random Error

16. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?
Random Error
What is the assumed reading error for an analog instrument?

17. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?
Random Error
What is the assumed reading error for an analog instrument?
+/- 0.5 of lowest measurement increment

18. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?
Random Error
What is the assumed reading error for an analog instrument?
+/- 0.5 of lowest measurement increment
What is the assumed reading error for a digital instrument?

19. Review Quiz
Which type of error can be minimized by averaging over repeated measurements?
Random Error
What is the assumed reading error for an analog instrument?
+/- 0.5 of lowest measurement increment
What is the assumed reading error for a digital instrument?
+/- 0.5 of least significant digit in the readout

20. Review Quiz
When you turn on a voltmeter, it reads 0.3 V and goes back to this value after every use. What type of error is this? Does the error most affect accuracy or precision?

21. Review Quiz
When you turn on a voltmeter, it reads 0.3 V and goes back to this value after every use. What type of error is this? Does the error most affect accuracy or precision?
Systematic error, zero error, accuracy

22. Review Quiz
When you turn on a voltmeter, it reads 0.3 V and goes back to this value after every use. What type of error is this? Does the error most affect accuracy or precision?
Systematic error, zero error, accuracy
How many significant figures are there in ?

23. Review Quiz
When you turn on a voltmeter, it reads 0.3 V and goes back to this value after every use. What type of error is this? Does the error most affect accuracy or precision?
Systematic error, zero error, accuracy
How many significant figures are there in ? 7

24. Review Quiz
Explain how you would quantify random error.

25. Review Quiz Explain how you would quantify random error.
Best judgment applied to qualitative observations
Standard deviation

26. Review Quiz Explain how you would quantify random error.
Best judgment applied to qualitative observations
Standard deviation
What is the next step after you have created a scatter plot of your data?

27. Review Quiz Explain how you would quantify random error.
Best judgment applied to qualitative observations
Standard deviation
What is the next step after you have created a scatter plot of your data?
Line of Best Fit (LOBF)

28. Review Quiz
When computing the slope of the line of best fit, do you use data points or points on the line of best fit?

29. Review Quiz
When computing the slope of the line of best fit, do you use data points or points on the line of best fit?
Line of Best Fit

30. Review Quiz
When computing the slope of the line of best fit, do you use data points or points on the line of best fit?
Line of Best Fit
When computing slope for a line of best fit, is it better to use points that are close together or far apart?

31. Review Quiz
When computing the slope of the line of best fit, do you use data points or points on the line of best fit?
Line of Best Fit
When computing slope for a line of best fit, is it better to use points that are close together or far apart?
Far apart

32. Multiplicative Changes
Common standardized test question
Common IB exam question
What happens if c = 4?

33. Multiplicative Changes
Common standardized test question
Common IB exam question
What happens if x increases by 4 times?

34. Multiplicative Changes
What happens if tension (T) is cut in half?

35. Multiplicative Changes
What happens if tension (T) is cut in half?

36. Linear Graphs y = mx +b b is the y-intercept
The value of y when x = 0
y is the dependent variable
x is the independent variable
We manipulate x to determine its effect on y

37. Linear Graphs y = mx +b b is the y-intercept
We like linear graphs because they show a direct correlation between dependent and independent variables!
Linear Graphs
y = mx +b
b is the y-intercept
The value of y when x = 0
y is the dependent variable
x is the independent variable
We manipulate x to determine its effect on y

38. Getting A Linear Graph
y vs. x

39. Getting A Linear Graph
y vs. x2
y vs. x

40. Getting A Linear Graph
y vs. 1/x
y vs. x

41. Interpreting Graphs
What does this graph tell you?

42. Interpreting Graphs What does this graph tell you? Velocity vs. time
Units (m/s, s)
Deceleration
Uniform Deceleration
Positive then negative

43. Interpreting Graphs
What does this graph tell you?

44. Interpreting Graphs What does this graph tell you? Vert posn vs. time
Units (m, s)
Deceleration
Uniform Decel
Pos/ neg velocity
Max 2 sed
Init/Final v = 0
Parabolic motion

45. Interpreting Graphs
What does this graph tell you?

46. Interpreting Graphs What does this graph tell you? Velocity vs. time
Units (m/s, s)
High initial acceleration
Rate of acceleration decreases to zero ending in constant velocity

47. Sine Curves Vertical displacement versus position Determine: Amplitude
Wavelength

48. Sine Curves Vertical displacement versus time Determine: Amplitude
Period

49. Sine Curves
What would a cosine curve look like?

50. Sine Curves What would a cosine curve look like?
Same thing, only it would start at max displacement instead of 0

51. Common Assumptions
Mechanics

52. Common Assumptions Mechanics “Bodies” are treated as point particles
“Frictionless” surface
Air resistance is negligible
Mass of strings, cables, springs, etc. are neglibigle

53. Common Assumptions
Thermal Physics

54. Common Assumptions Thermal Physics “Ideal” gas
Intermolecular forces are negligible
“Isolated” system

55. Common Assumptions Electricity
Power sources have no internal resistance
Wires and ammeters have no resistance
Voltmeters have infinite resistance

56. Assumptions: Da Rules Always state your assumptions
State how realistic your assumptions are, i.e. are they justified
State how your results may be affected by your assumptions

57. Dat’s it

58. Essential Idea
Scientists aim towards designing experiments that can give a “true value” from their measurements, but due to the limited precision in measuring devices, they often quote their results with some form of uncertainty.

59. Understandings Random and systematic errors
Absolute, fractional and percentage uncertainties
Error bars
Uncertainty of gradient and intercepts

60. Applications And Skills
Explaining how random and systematic errors can be identified and reduced
Collecting data that include absolute and/or fractional uncertainties and stating these as an uncertainty range (expressed as: best estimate ± uncertainty range)
Propagating uncertainties through calculations involving addition, subtraction, multiplication, division and raising to a power
Determining the uncertainty in gradients and intercepts

61. Guidance
Analysis of uncertainties will not be expected for trigonometric or logarithmic functions in examinations

62. Data Booklet ReferenceIf
Then
then

63. Physics in Everyday Life

64. Questions?

65. Homework
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