1. Physics 1710—Section 4 Instructor—Matteson Session #2 Chapter 1 Measurement

2. Name_______Seat # ____ Date _______ Session #2 Response Card # ________ (Tell me if you do not have one) E-mail address _______@____.___ (if you did not receive message from Matteson@unt.edu) Joe College Seat# 53 1/14/02 Session #1 Foolscap “Quiz” Physics 1710—Chapter 1 Measurement

3. Fact: The earth has a circumference of approximately 40 million meters (4. X 10 7 m). How fast must one move on average to travel around the world in 80 days? Physics 1710—Chapter 1 Measurement

4. 1′ Lecture First 3 Fundamental Units: First 3 Fundamental Units: –Time, measured in seconds = 1/86 400 of m.s. day –Length, measured in meters = c (1/299 792 458 sec) –Mass, measured in kilograms = specimen Prefixes scale units to convenient size. Prefixes scale units to convenient size. Density is mass per unit volume. [kg/m 3 ] Density is mass per unit volume. [kg/m 3 ] Avogadro’s number is the number of atoms in a mole of an element, N Avogadro = 6.022x10 23 Avogadro’s number is the number of atoms in a mole of an element, N Avogadro = 6.022x10 23 Significant figures tell the tale. Significant figures tell the tale. Scientific notation saves ink. Scientific notation saves ink. Physics 1710—Chapter 1 Measurement

5. Q&A: Q: Is this class mainly for engineers? I ask this because I am pre-med. Does this course apply to my field? A(s): No, it is for scientists as well. Yes, it does apply to your field. Yes, it does apply to your field. You will learn facts about how things move, e.g. consider muscles, joints, blood, air. You will learn facts about how things move, e.g. consider muscles, joints, blood, air. You will grow an understanding of dynamics, e.g. energy, momentum and trauma. You will grow an understanding of dynamics, e.g. energy, momentum and trauma. You will develop analytical and qualitative skills, e.g. think about diagnosis and drug dosing. You will develop analytical and qualitative skills, e.g. think about diagnosis and drug dosing. This course is for all scientists and engineers. This course is for all scientists and engineers. Physics 1710—Chapter 1 Measurement

6. Laboratory Introduction Physics 1730 Dr. John Prince Physics 1710—Chapter 1 Measurement

7. Matteson’s Dicta Numbers 1 & 2: 1. Physics is that branch of science concerned with the interaction of matter-energy in space- time. 2. The physical universe consists of only matter and energy and the vacuum. Late breaking news: what about “dark matter” and “dark energy?” They are 95% of universe and we don’t yet know what they are. Late breaking news: what about “dark matter” and “dark energy?” They are 95% of universe and we don’t yet know what they are. Physics 1710—Chapter 1 Measurement

8. Measurement is the quantitative comparison of a physical parameter to a standard unit. Physics 1710—Chapter 1 Measurement “Existential Physics” Activity: Measure the width of the top of your desk in “hands.”

9. Why did we observe a variety of values in our measurement? Physics 1710—Chapter 1 Measurement Measurement is the quantitative comparison of a physical parameter to a standard unit. ‽ A “hand” is not a standard unit. Our measurement is subject to error. Our measurement is subject to error. Our measurement is coarse. Our measurement is coarse.

10. Measurement is the quantitative comparison of a physical parameter to a standard unit. Therefore we need standards. Accuracy is the difference of a measurement from the (unknown) true value. All measurement contain experimental error. Precision is the “fineness” of the division of the scale used to compare to the standard unit. Precision limits our knowledge. Physics 1710—Chapter 1 Measurement

11. 80/20 Precision is the fineness of a measurement. 80/20 Accuracy is the correspondence of a measurement to an (unknown) true value. Less precise Less accurate Standard Measurement Physics 1710—Chapter 1 Measurement

12. What numbers one writes down reveals one’s knowledge (and ignorance) of the actual true (but unknown) value. Example: 2. 2.0 2.01 2.0085 2.00852 represent the values of a measurement at various levels of precision. Physics 1710—Chapter 1 Measurement Significant figures:

13. When multiplying (or dividing) numbers, round result to same number of significant figures as the factor with least number of significant figures.When multiplying (or dividing) numbers, round result to same number of significant figures as the factor with least number of significant figures. When adding (or subtracting), first round to same decimal place as contribution with the least precision, then compute.When adding (or subtracting), first round to same decimal place as contribution with the least precision, then compute. Physics 1710—Chapter 1 Measurement Rules for Computing with Significant Figures:

14. Physics 1710—Chapter 1 Measurement Rules for Rounding If remainder is less than 5, truncate, i.e. round down. Example: 3.1415927… ~ 3.14 If remainder is larger than 5, round up. Example: 3.1415927… ~3.1416 If remainder is exactly 5, round up or down to leave last digit even. Example: 31½ = 31.5000… ~32.

15. Scientific Notation Number = Mantissa x 10 Exponent = _._____ E__ Big Numbers: 1.234567 x 10 3 = 1234.567 Small Numbers: 1.234567 x 10 –2 = 0.01234567 Physics 1710—Chapter 1 Measurement

16. Activity: Enter: “1.234567” ; “EXP” or “EE”; “03” Display should read: “1.234567 03” or “1.234567E03” Enter: “1.234567”; “EXP”; “03” ; “+/-” or “⇄” or “(-)” Display should read: “ “1.234567 -03 ” or “1.234567E-03” Physics 1710—Chapter 1 Measurement Know Your Calculator

17. 17701780179018001810 Physics 1710—Chapter 1 Measurement Fundamental Units Système International de Metrique (SI)— “Metric System” First introduced in France in 1799—(on Napoleon’s coup) La $ American Rev US Constitution French Rev Napoleon

18. Physics 1710—Chapter 1 Measurement Time Standard: second [s] (1/60)(1/60)(1/24) =1/86,400 mean solar day (1/60)(1/60)(1/24) =1/86,400 mean solar day 9,192,631,770 (exactly) times the period of vibration of a Cesium-133 atomic clock. 9,192,631,770 (exactly) times the period of vibration of a Cesium-133 atomic clock. Time Demonstration Time Demonstration

19. Length standard: meter [m] Meter defined in 1799, by Napoleon’s Republic.Meter defined in 1799, by Napoleon’s Republic. 1/10 7 quadrant of Earth; C  = 4.00x 10 7 m1/10 7 quadrant of Earth; C  = 4.00x 10 7 m Distance light travels in 1/299,792,458 secDistance light travels in 1/299,792,458 sec Meter DemonstrationMeter Demonstration Physics 1710—Chapter 1 Measurement

20. Derived Units of area and volume Area: 10 m x 10 m = 100 m 2 = 1 are Area: 10 m x 10 m = 100 m 2 = 1 are 100 ares = 1 hectare = 1x10 4 m 2 1 US acre = 0.4046 ha Volume: m x m x m = m 3 = 1000 liter = 1000 l Volume: m x m x m = m 3 = 1000 liter = 1000 l e.g. 1000 cm 3 = 1 liter 1 US gallon = 3.7854118 liters ~ 3.8 l Physics 1710—Chapter 1 Measurement

21. Mass Standard : kilogram [kg] kilo = 1000, 1 kg = 1000 gram kilo = 1000, 1 kg = 1000 gram 1 kg is the mass of approximately 1/1000 m 3 (=1 liter) of water 1 kg is the mass of approximately 1/1000 m 3 (=1 liter) of water Mass is a fundamental property of all matter. Mass is a fundamental property of all matter. Each atom has a mass of ~1.66 x 10 -27 kg times its “atomic mass number” Each atom has a mass of ~1.66 x 10 -27 kg times its “atomic mass number” Physics 1710—Chapter 1 Measurement

22. Mass Standard : kilogram [kg] 1 kg weighs on earth about 2.2 pounds.1 kg weighs on earth about 2.2 pounds. Physics 1710—Chapter 1 Measurement

23. Amedo Avogadro (1776-1856) Italian Physicist Italian Physicist Proposed Avogadro’s Law (1811) Proposed Avogadro’s Law (1811) Physics 1710—Chapter 1 Measurement 22.8 liters = 1 mole of gas = 6.022 x10 23 molecules or atoms 12 g C = 1 mole

24. N A = 6.0221367(28) x 10 23 atoms/mole Atomic mass unit = u u = 1.660 540 2(10) x 10 –27 kg (~ 1 2 / 3 yoctogram) N A ‧ u = 1.00 x 10 –3 kg = 1.00 gram N A is the number of atoms in one “gram molecular weight” of an element. Avogadro’s Number Physics 1710—Chapter 1 Measurement

25. Practice: How much does a 5 US Gal can of water weigh? Density of water = 1.0 kg/l M = ρ V = (1.0 kg/l )(5 gal x 3.8 l/gal) = 19. kg W = 2.2 lbs/kg x 19. kg = 42. lbs Physics 1710—Chapter 1 Measurement

26. Summary Fundamental Dimensions and UnitsFundamental Dimensions and Units Time, measured in seconds; Length, measured in meters; Mass, measured in kilograms. Prefixes scale units to convenient size. k =1000, M = 1 000 000 c = 1/100, m = 1/1000, μ =1/1 000 000 Prefixes scale units to convenient size. k =1000, M = 1 000 000 c = 1/100, m = 1/1000, μ =1/1 000 000 Density is mass per unit volume. ρ = m/V [kg/m 3 ] Density is mass per unit volume. ρ = m/V [kg/m 3 ] Avogadro’s number is the number of atoms in a mole of an element. 6.022 x10 23 atom/mole Avogadro’s number is the number of atoms in a mole of an element. 6.022 x10 23 atom/mole Physics 1710—Chapter 1 Measurement

27. 1′ Essay What was that about? What was that about? An “Aha!” An “Aha!” A Question A Question Turn in Foolscap. Come to Recitation in Room 102 1:00 p.m. Today! Physics 1710—Chapter 1 Measurement