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AP Physics. Chapter 1: Measurement. Intro to Physics. Classical Physics- Mechanics (Newton) Thermodynamics (Watt/Carnot/Diesel) Optics (Huygens/Young/Fresnel) Electricity and Magnetism (Maxwell) Solid understanding Prior to 1900’s. Intro. Modern Physics Late 1800’s
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AP Physics Chapter 1: Measurement
Intro to Physics • Classical Physics- • Mechanics (Newton) • Thermodynamics (Watt/Carnot/Diesel) • Optics (Huygens/Young/Fresnel) • Electricity and Magnetism (Maxwell) • Solid understanding Prior to 1900’s
Intro • Modern Physics • Late 1800’s • Discoveries made that cannot be explained by theories of Classical Physics • Relativity (motion at/near c) [Einstein] • Quantum Mechanics (atomic structure/behavior) [Bohr, Heisenberg, deBroglie, Schrodinger etc) • Onset of the Nuclear Age
Intro • Where are we now? • Unify General Relativity and Quantum Mechanics (macroscopic) (microscopic) • GUT/TOE • Current Research/Theories- • Higgs-Boson: early indications that it does in fact exist • Statistical Probability of approximately “5 sigma” • Non-zero Mass Neutrinos • String Theory (M-Theory) multidimensional (11)
1.1 Standards of Measurement Standardized System of Measurement allows collaboration/repetition/verifcation Basic Quantities- (Mechanics) Length Mass Time Derived Quantities- Combinations of basics Ex: Force = mass x length/time2
1.1 • Standards- International System of Units (Le Systeme International d’unites- SI) • Length Meter (m) • Distance light travels in 1/299792458th sec
1.1 • Mass International Standard Kilogram (Kg) • Kg Standard Platinum-Iridium Alloy Cylinder • Height = Diameter (39.17 mm) minimizes surface area • Incredibly low Reactivity • Held at IBWM, Sevres France • Copies Distributed to other Nations (US held at NIST)
1.1 • Time second (s) • Cesium-133 Atomic Fountain Clock • 1 second based on resonant frequency of 9,192,631,770 radiation oscillations (periods of vibration). • Will not gain/lose a second in 100 million years.
1.1 Metric Prefixes See Table 1.4 (page 7) KNOW 10-9 - 109 (reference for others) Scientific Notation Generally used for numbers smaller/larger than 10-3 - 103
1.2 Modeling • Models- THEORY used to account for observed phenomenon/make reliable predictions Ex: Theory of Matter Matter-> Atom -> Sub-atomic particles-> Quarks-> Strings?
1.3 Density and Atomic Mass • Density- Mass per unit volume (length3) • (rho) units: kg/m3 g/cm3 • Atomic Mass- single atom expressed in AMU (1 u = 1.660 538 7 x 10-7 kg) • Remember : • 1 mole = 6.02x1023 atoms • Molar Mass = Atomic Mass in grams • Solve Example 1.1 Page 10
1.4 Dimensional Analysis • Dimension- Physical Nature of a Quantity Length (L) Mass (M) Time (T) Area (L2) Volume (L3) Speed (L/T) Accel (L/T2) Deriving/Verifying Expressions- Dimensions treated as algebraic quantities, same on both sides of expression. Only add/subtract like dimensions.
1.4 • Try a couple
1.5 Converting Units • Different Standards within a given dimension. Ex: 1 mi = 1609 m Units are also treated as algebraic quantities. Ex: Convert 5’ 10” -> m
1.6 Estimates and Order of Magnitude • Quick Estimates when an exact answer is not needed. • Order of Magnitude (nearest power of 10) • Ex: 0.0082 -> .01 -> 10-2 • Ex: 365 -> 400 -> 4x102 • Up/Down work out • Try Estimating: • Steps across the US • Breaths in a lifetime
1.7 Significant Figures and Uncertainty • Significant Figures • Measurement Precision • Measurements Estimated between smallest marking • Ex: 20.25 cm ± 0.03 cm • Problem Solving • Generally Keep the fewest number of S.F. given • Usually 3
1.7 • Uncertainty Calculations • 2 Methods • Treat Measurement and Uncertainty like a Binomial to calculate. Ex: Find the area of 10.0 m ± 0.1 m by 5.0 m ± 0.1 m
1.7 • Or Add the two fractional (%) uncertainties. • Same Example • Problems • Black# = Straightforward • Blue# = Intermediate • Pink# = Challenging • Box# = Full Solution in Study Guide (See me) • WWW = Resources/coaching at www.pse6.com **
HW • 4, 9, 11, 12, 20, 22, 31, 49, 55, 61