2. Unit 1 Introduction

3. Measurement

4. To make a measurement, we must...  know what we are trying to measure  have some standard with which to compare  must have some method of making this comparison

5. SI Units  French scientists adopted the metric system in 1795.  Major Benefit: Units are related by __________________.  There are seven base units. We will be concerned with only five for now.

6. Fundamental SI Units for Physics  length  time  _________________________  mass  _________________________  Light (Candela)

7. How might you define a second? Class discussion

8. Time

9. “The ____________ between two occurrences.”  The SI unit of time is the second.  Originally defined as 1/86 400th of the average length of a day.  Redefined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine level of the fundamental state of the atom of Cesium-133 isotope.

10. Length

11. “The ______________ between two points.”  The SI unit of length is the meter.  Originally defined as 1/10 000 000 of the distance between the North Pole and the equator through Paris, France.  Redefined as 1 650 763.73 times the wavelength of the orange-red Krypton 86 isotope at 1.013 bar and 15 oC.  Currently defined as the distance light travels through a vacuum in 1/299 792 458th of a second.

12. Temperature

13. “A measure of the ______ of a substance.”  Heat is a form of energy which is the result of molecular motion.  Temperature scales:  Kelvin (Absolute scale) (SI UNIT)  Celsius  Fahrenheit

14. Mass

15. “A measure of the __________in an object.”  The SI unit of mass is the kilogram.  Originally defined as the mass of 1 Liter of water at 3.98 oC.  Now defined as the mass of a piece of metal kept at the International Bureau of Weights and Measures in Sevres, France.

16. Which weighs more, a ton of feathers or a ton of lead?

17. Mass vs. Weight  “A measure of the amount of __________ in an object.”  Does not change from place to place.  SI unit is the kilogram.  “A measure of the ______________ force between objects.”  Changes from place to place.  SI unit is the Newton.

18. Quantity

19. “The ____________ of substance one has.”  In the scientific community, substances are referred to in moles (SI unit).  One mole is 6.02 x 1023 particles (Avogadro's #).  12 g of Carbon-12

20. The Mole  A mole of _________ would spread over the surface of the earth, and produce a layer about 50 miles thick.  A mole of _______, spread over the United States, would produce a layer 3 inches deep.  A mole of dollars could not be spent at the rate of a billion dollars a day over a _________ years.  This shows you just how big a mole is. This number is so large that it is usually only represented in scientific notation

21. Scientific Notation  A method of expressing _________________ as powers of ten.  Mostly useful when expressing rather large or small numbers/quantities.  Example:  2.03x102 = _______________  0.0678 = _______________

22. Advantages of Scientific Notation  Easily able to express very large or small numbers.  Number of molecules in 18 mL of water  602 000 000 000 000 000 000 000  The mass of an electron  0.000 000 000 000 000 000 000 000 000 000 911 kg

23. Converting between decimals & scientific notation #Direction to move decimal # of places Positive or negative 100Left2+10 2 10Left1+10 1 1n/a0010 0.1Right1-10 -1.01Right2-10 -2

24. Converting Between Scientific Notation & Decimals #Direction to move decimal # of places Smaller or greater than “1” 1.0x10 3 right3greater1000 1.0x10 2 right2greater100 1.0x10 0 n/a0 1 1.0x10 -2 left2smaller.01.01 1.0x10 -3 left3smaller.001

25. To express a Decimal Number in S.N. (#.##X10#)  Example:  605 = 605.0  We always move the decimal so that we have only ONE digit to the _______ of the decimal.  605.0 = 6.05 (we had to move the decimal two places)  For every place holder the decimal moves, you +/- 1 from the exponent/power on the “10.”  6.05x10 2

26. Multiplying two #’s expressed in scientific notation.  Multiply the digits.  ___________________________  If necessary, re-write in proper scientific notation.  Check the number of significant digits.

27. Dividing two #’s expressed in scientific notation.  _________________________  Subtract the exponents.  If necessary, re-write in proper scientific notation.  Check the number of significant digits.

28. Prefixes  We use prefixes as a __________________ way of expressing large multiples of 10.  For instance we use the prefix kilo- to represent 1000 or 10 3

29. Prefix Table http://kaffee.netfirms.com/Science/images/SI.Prefixes.Chart.gif

30. Prefix Responsibility http://kaffee.netfirms.com/Science/images/SI.Prefixes.Chart.gif

31. Derived Units  “Units which are the result of combinations of two or more fundamental units.”

32. Derived Units  What are some other units that are not base units, but units that we see on a regular basis?  Examples: – Newton (N)kg * m/s 2 – Joules (J)N * m – Density ( ρ ) g/cm 3

33. Measurement Reliability

34. Accuracy and Precision  ______________:  “How closely a measurement is to the true correct value for the quantity.”  _______________:  “How closely a set of measurements are to each other.”

35. Accurate or Precise?

36. Significant Digits/Figures The reliable digits in a measurement based on the accuracy of the measuring instrument.

37. Rule of Thumb  Whenever making a measurement, you are permitted one “guessed” digit.  The guessed digit is the last significant digit in a number.

38. Significant Digit Demonstration  Graduated Cylinder and Beaker

39. Rules to determine the number of significant digits.  Non-zero numbers are significant.  123 cm  Zeros between two significant digits are significant.  103 cm  Final zeros after a decimal point are significant.  10.70 in.  Zeros used solely for spacing the decimal point are not significant.  186 000 miles/sec.  0.00000186 miles/sec

40. During Addition and Subtraction  Your answer should be rounded off to the decimal place value as the measurement with the guessed digit in the _____________ decimal place.

41. Add the following values. 100.01 cm + 3.0 cm

42. Add the following values. 241 cm + 64,300 cm

43. During Multiplication and Division  The final answer should have the same number of significant digits as the measurement having the smallest number of significant digits.

44. Multiply the following values. 44 m x 2 m

45. Rules for Rounding Numbers  If the digit to the immediate right of the last significant figure is less than five, do not change the last significant figure.  2.532  _____________

46. Rules for Rounding Numbers  If the digit to the immediate right of the last significant figure is greater than ________, round up the last significant figure.  2.536  ______________

47. Rules for Rounding Numbers  If the digit to the immediate right of the last significant figure is equal to five and is followed by a nonzero digit, round up the last significant figure.  2.535 1  _______________

48. Rules for Rounding Numbers  If the digit to the immediate right of the last significant figure is equal to five and is not followed by a nonzero digit, look at the last significant figure. If it is an odd digit, round it up. If it is an even digit, do not round up.  2.535 0  _______________  2.525 0  _______________

49. Percent Error – Two common versions

50. Percent Error Example problem  Determine the percent error for the density of Al found experimentally to be equal to 2.60 g/cm 3 if the actual density is 2.70 g/cm 3.

51. Parallax  The apparent shift in objects when viewed from different _____________.  Can be used to discern the distance of the object(s) being observed.

52. Dimensional Analysis

53.  “A problem solving method that focuses on the units that are used to describe matter.”  Simply put, it is the analysis of the units in a problem to see if the math was done right.

54. Dimensional Analysis  Example Problem:  A person is traveling 70.0 mph for 10.0 seconds. How far did they travel in feet?

55. Conversion Factor  “A ratio of equivalent values used to express the same quantity in different units; is always equal to 1 and changes the units of a quantity without changing its value.”

56. Dimensional Analysis  How many inches are in 2.7 feet?

57. Question  It is possible to use dimensional analysis to convert between units?  Since 1 m = 1000 mm, how many mm are there in 3.45 m?

58. Example  How many cm 3 are in 3.2 m 3 ?

59. Example  In Canada, a car travels along Highway 401 at a speed of 100.0 km/h. What is the car’s speed in m/s?

60. Scientific Process Review

61. REVIEW…  Data Representation  Types of Graphs  What constitutes a good graph?  Independent vs. Dependent Variables

62. Variables  Independent (x-axis) – the variable(s) being manipulated by the scientist.  Dependent (y-axis) – the variable(s) that are the observed result of the independent variables being manipulated by the scientist.  Note: You will not always have a clear independent and dependent variable. Usually this happens when you are dealing with rates (units per given time). In this case time always goes on the x-axis.