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Chapter 1-7

Chapter 1-7. MASTER NOTES. MASTER CLASS NOTES FOR Chapter 1,2,3,4, & 7. Chapter 1. The Science of Physics. Table of Contents. Chapter 1 The Science of Physics Chapter 2 Motion in One Dimension Chapter 3 Two- Dimensional Motion and Vectors Chapter 4 Forces and the Laws of Motion

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Chapter 1-7

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  1. Chapter 1-7 MASTER NOTES MASTER CLASS NOTES FOR Chapter 1,2,3,4, & 7

  2. Chapter 1 The Science of Physics Table of Contents Chapter 1 The Science of Physics Chapter 2 Motion in One Dimension Chapter 3 Two- Dimensional Motion and Vectors Chapter 4 Forces and the Laws of Motion Chapter 7 Rotational Motion and the Law of Gravity

  3. Section 1 What is Physics Chapter 1 The Topics of Physics • Physics is simply the study of the physical world.

  4. Section 1 What is Physics Chapter 1 The areas of Physics 1. Mechanics- The study of motion and its causes. • Falling objects, friction, weight, spinning objects. 2. Thermodynamics – The study of heat and temperature. • Melting and Freezing processes, engines, refrigerators. 3. Vibration and Wave Phenomena – The study of specific types of repetitive motion. • Springs, pendulums, sound

  5. Section 1 What is Physics Chapter 1 The areas of Physics (cont) 4. Optics – The study of light. • Mirrors, lenses, color, astronomy 5. Electromagnetism – The study of electricity, magnetism, and light. • Electrical charge, circuitry, permanent magnets, electromagnets. 6. Relativity – The study of particles moving at any speed, including very high speed. • Particle collisions, particle accelerators, nuclear energy.

  6. Section 1 What is Physics Chapter 1 The areas of Physics (cont.) 7. Quantum Mechanics – The study of submicroscopic particles. • The atom and its parts

  7. Chapter 1 Types of observations • Qualitative- descriptive, but not true measurements • Hot • Large • Quantitative- describe with numbers and units • 100C • 15 meters

  8. Section 1 What is Physics Chapter 1 The Scientific Method • Thescientific methodis a way to ask and answer scientific questions by making observations and doing experiments. • Steps of the scientific : • Observation (Ask a Question) • Collect Data (Do Background Research) • Construct a Hypothesis (Educated guess) • Test Your Hypothesis by Doing Experiments • Analyze Your Data and Draw a Conclusion • The conclusion is only valid if it can be verified by other people. • Communicate Your Results

  9. Section 1 What is Physics? Chapter 1 The Scientific Method

  10. Section 1 What is Physics Chapter 1 The Scientific Method (cont) • System – A set of items or interactions considered a distinct physical entity for the purpose of study. • Decide what to study and eliminate everything else that has minimal or no effect on the problem. • Draw a diagram of what remains (Model) • Models – A replica or description designed to show the structure or workings of an object, system, or concept. • Models help guide experimental design

  11. Section 1 What is Physics? Chapter 1 The System

  12. Section 1 What is Physics? Chapter 1 The Scientific Model

  13. Section 1 What is Physics Chapter 1 The Scientific Method (cont) • Hypothesis – A reasonable explanation for observations, one that can be tested with additional experiments. • The hypothesis must be tested in a controlled experiment. • Controlled Experiment- Only one variable at a time is changed to determine what influences the phenomenon you are observing.

  14. Section 2 Measurements in Experiments Chapter 1 Numbers As Measurements • Numerical measurements in science contain the value (number) and Dimension. • Dimension is the physical quantity being measured (length, mass, time, temperature, electric current) • Each dimension is measured using units and prefixes from the SI system. • The dimension must match the unit. (ex. If you are measuring length, use the meter(m), not the kilogram(kg)

  15. Section 2 Measurements in Experiments Chapter 1 • SI is the standard measurement system for science. • Used so that scientists can communicate with the same language. • There are seven base units. They are: • Meter(m) – length • kilogram(kg) – Mass • Second(s) – Time • Kelvin(K) – Temperature • Ampere(A) – current • Mole(mol) – amount of substance • Candela(cd) – luminous intensity

  16. Section 2 Measurements in Experiments Chapter 1 • Common Metric Prefixes: -See handout or visit reference section of website -Be able to convert between any prefix and another.

  17. How good are the measurements? • Scientists use two word to describe how good the measurements are: • Accuracy- how close the measurement is to the actual value. • Precision- how well can the measurement be repeated.

  18. Differences • Accuracy can be true of an individual measurement or the average of several. • Problems with accuracy are due to error • Precision requires several measurements before anything can be said about it. • Precision describes the limitation of the measuring instrument.

  19. Percent Error • Percent error = (Experimental Value – Accepted value) x 100 Accepted Value • Percent error can be negative.

  20. Let’s use a golf analogy

  21. Accurate? No Precise? Yes

  22. Accurate? Yes Precise? Yes

  23. No Precise? Maybe? Accurate?

  24. Accurate? Yes Precise? We cant say!

  25. Significant Figures Scientific Notation Accuracy and Precision

  26. 1 2 3 4 5 Significant figures (sig figs) • How many numbers mean anything. • When we measure something, we can (and do) always estimate between the smallest marks.

  27. Significant figures (sig figs) • The better marks the better we can estimate. • Scientist always understand that the last number measured is actually an estimate. 1 2 3 4 5

  28. 142 141 Significant figures (sig figs) • The measurements we write down tell us about the ruler we measure with • The last digit is between the lines • What is the smallest mark on the ruler that measures 142.13 cm?

  29. Sig figs. • How many sig figs in the following measurements? • 458 g • 4085 g • 4850 g • 0.0485 g • 0.004085 g • 40.004085 g • 405.0 g • 4050 g • 0.450 g • 4050.05 g • 0.0500060 g

  30. Rounding rules • Look at the number behind the one you’re rounding. • If it is 0 to 4 don’t change it. • If it is 5 to 9 make it one bigger. • Round 45.462 to four sig figs. • to three sig figs. • to two sig figs. • to one sig figs. 45.46 45.5 45 50

  31. Scientific notation • All non-zero digits in scientific notation are significant figures. • Any ending zero will be after the decimal point to be significant • 1.20 x 103 • Sometimes you must write in scientific notation to use the correct sig figs.

  32. Watch the Sig Figs • When rounding, you don’t change the size of the number. • You should end up with a number about the same size. • Use place holders- they’re not significant. • Round 15253 to 3 sig figs • Round 0.028965 to 3 sig figs 15300 0.0290

  33. Atlantic Pacific Present Absent If the decimal point is absent, start at the Atlantic (right), find the first non zero, and count all the rest of the digits 230000 1750

  34. Atlantic Pacific Present Absent If the decimal point is PRESENT, start at the Pacific (left), find the first non zero, and count all the rest of the digits 0.045 1.2300

  35. Using your calculatorwith scientific notation • EE and EXP button stand for x 10 to the • 4.5 x 10-4 • push 4.5 • push either EXP or EE • push 4 +/- or -4 • see what your display says.

  36. Practice these problems • (4.8 x 10 5 ) x (6.7 x 10-6) • Remember when you multiply you add exponents • 106x 10-4 • When you divide you subtract exponents. • (6.8 x 10 -6) • (3.2 x 10 4)

  37. Adding and Subtracting • You can’t add or subtract numbers until they are to the same power of ten. • Your calculator does this automatically. • (4.8 x 10 5 ) + (6.7 x 106) • (6.8 x 10 -6) - (3.2 x 10-5) • Remember- standard form starts with a number between 1 and 10 to start.

  38. Adding and subtracting with sig figs • The last sig fig in a measurement is an estimate. • Your answer when you add or subtract can not be better than your worst estimate. • have to round it to the least place of the measurement in the problem.

  39. 27.93 + 6.4 27.93 27.93 + 6.4 6.4 For example • First line up the decimal places Then do the adding.. Find the estimated numbers in the problem. 34.33 This answer must be rounded to the tenths place.

  40. Practice • 4.8 + 6.8765 • 520 + 94.98 • 0.0045 + 2.113 • 500 -126 • 6.0 x 103 - 3.8 x 102 • 6.0 x 10-2 - 3.8 x 10-3 • 5.33 x 1022 - 3.8 x 1021

  41. Multiplication and Division • Rule is simpler • Same number of sig figs in the answer as the least in the question • 3.6 x 653 • 2350.8 • 3.6 has 2 s.f. 653 has 3 s.f. • answer can only have 2 s.f. • 2400

  42. Multiplication and Division • Same rules for division. • practice • 4.5 / 6.245 • 4.5 x 6.245 • 9.8764 x .043 • 3.876 / 1980 • 16547 / 710

  43. The Metric System

  44. Measuring • The numbers are only half of a measurement. • It is 10 long. • 10 what? • Numbers without units are meaningless. • How many feet in a yard? • A mile? • A rod?

  45. The Metric System • Easier to use because it is a decimal system. • Every conversion is by some power of 10. • A metric unit has two parts. • A prefix and a base unit. • prefix tells you how many times to divide or multiply by 10.

  46. Base Units • Length - meter - more than a yard - m • Mass - grams - about a raisin - g • Time - second - s • Temperature - Kelvin or ºCelsiusK or ºC • Energy - Joules- J • Volume - Liter - half of a two liter bottle- L • Amount of substance - mole - mol

  47. Prefixes • kilo k 1000 times • deci d 1/10 • centi c 1/100 • milli m 1/1000 • micro μ1/1000000 • nano n 1/1000000000 • kilometer - about 0.6 miles • centimeter - less than half an inch • millimeter - the width of a paper clip wire

  48. Volume • calculated by multiplying L x W x H • Liter the volume of a cube 1 dm (10 cm) on a side • 1L = 1 dm3 • so 1 L = 10 cm x 10 cm x 10 cm • 1 L = 1000 cm3 • 1/1000 L = 1 cm3 • 1 mL = 1 cm3

  49. Volume • 1 L about 1/4 of a gallon - a quart • 1 mL is about 20 drops of water or 1 sugar cube

  50. Mass • 1 gram is defined as the mass of 1 cm3 of water at 4 ºC. • 1000 g = 1000 cm3 of water • 1 kg = 1 L of water

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