Physics 111, Fall 2005 Classical Mechanics Prof. Haimin Wang

My Research: Solar Physics Instrumentation Magnetic Fields and Solar Activity

Week 1  Chapter 1 Sections 1–7 –Measurement –International System of Units (SI System) –Conversion of Units –Length –Time –Mass

Measurements  Use laws of physics to describe many different physical systems –Small set of simple laws –Common language is mathematics  Test laws by experiments –Select smallest set of standards and derive other standards –International Bureau of Weights and Measures (Paris), National Bureau of Standards, etc. –Système Internationale (SI), International System of Units, metric system, or mksA system

SI Units Length meter m Masskilogramkg Timeseconds Electric currentampereA Thermodynamic temperaturekelvinK Luminous intensitycandelacd Amount of substancemolemol

10 x PrefixSymbol x=18 exaE 15 petaP 12 teraT 9 gigaGGeV 6 megaMMeV 3 kilokkeV 2 hectoh 1 decada Prefixes for SI Units

10 x PrefixSymbol x =  1 decid  2 centiccm  3 millimmm  6 microµµm  9 nanonNm  12 picopPm  15 femtoffm  18 attoa Prefixes for SI Units

Example of Length MeasurementsLength (m) Distance to 1 st galaxies2x10 26 Distance to Nearest Star (Proxima Centauri) 4x10 16 Distance to Pluto6x10 12 Radius of Earth6x10 6 Height of Mt. Everest9x10 3 Thickness of this page1x10 -4 Radius of hydrogen atom5x Radius of a proton1x10 -15

Time  1 second is the time taken by 9,192,631,770 oscillations of the light emitted by cesium-133 atom  Speed of light c=299,792,458 m/s

Example of time MeasurementsTime (second) Age of Universe5x10 17 Length of a year3x10 7 Length of a day9x10 4 Lifetime of muon2x10 -6

Mass  Standard 1: a platinum-iridium cylinder in Paris  Standard 2: Carbon-12 has 12 atomic mass units (u). 1u= x kg

Example of mass ObjectsMass (kg) Sun2x10 30 Moon7x10 22 Ocean Liner7x10 7 Human Body6x10 Speck of dust7x Proton2x Electron9x10 -31

Units  Language is mathematics  Equations  Diagrams/visualization  Quantities have dimensions  Results have units  Consistency

Precision  Measurements –Uncertainties Absolute Percent –Calculation Result can not be better than data Use scientific notation to show significant figures –Examples = ,400,000 = x = 3 x 10 -3

Sample Problem 1-4, p6

Chapter 3: Vectors  Vectors and Scalars  Adding Vectors Geometrically  Components of Vectors  Unit Vectors  Adding Vectors by Components  Vectors and the Laws of Physics  Multiplying Vectors –Scalar Product –Vector or Cross Product

Vectors and Scalars DisplacementPath independence

Laws of Vector Addition

Components of Vectors

Unit Vectors and Coordinate Systems

Vector Multiplication Scalar product Vector/cross product

Sample Problem 3-4