Physics 111: Elementary Mechanics – Lecture 1 Carsten Denker NJIT Physics Department Center for Solar–Terrestrial Research

September 5, 2005Center for Solar-Terrestrial Research Week 1  Information  Chapter 1 Sections 1-7 Measurement Units Conversion of Units  Chapter 3 Sections 1-8 Adding and multiplying vectors Unit vectors

September 5, 2005Center for Solar-Terrestrial Research Objectives  By the end of Week 1 you should be able to List the SI units List typical prefixes of units Convert from the English to the metric system Add/subtract two vectors Explain the commutative and associative law Distinguish between scalar and vector product Work with trigonometric functions

September 5, 2005Center for Solar-Terrestrial Research 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

September 5, 2005Center for Solar-Terrestrial Research SI Units Length meter m Masskilogramkg Timeseconds Electric CurrentampereA Thermodynamic TemperaturekelvinK Luminous Intensitycandelacd Amount of Substancemolemol Why should we care about SI units? Mars Climate Orbiter:

September 5, 2005Center for Solar-Terrestrial Research 10 x PrefixSymbol x=18 exaE 15 petaP 12 teraT 9 gigaGGeV 6 megaMMeV 3 kilokkeV 2 hectoh 1 decada Prefixes for SI Units

September 5, 2005Center for Solar-Terrestrial Research 10 x PrefixSymbol x=-1 decid -2 centiccm -3 millimmm -6 microµµA -9 nanonnm -12 picoppm -15 femtoffm -18 attoa Prefixes for SI Units

September 5, 2005Center for Solar-Terrestrial Research Units  Language is mathematics  Equations  Diagrams/Visualization  Quantities have dimensions  Results have units  Consistency

September 5, 2005Center for Solar-Terrestrial Research 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

September 5, 2005Center for Solar-Terrestrial Research Vectors  AB displacement from A to B  BC displacement from B to C  AC displacement from A to C or sum or resultant of displacements AB and BC  Quantities that add like this are vectors  Vectors have magnitude and direction

September 5, 2005Center for Solar-Terrestrial Research Adding Vector Geometrically Commutative Law Associative Law Subtraction

September 5, 2005Center for Solar-Terrestrial Research Trigonometric Functions Please bring calculator to lecture and recitation!

September 5, 2005Center for Solar-Terrestrial Research Adding Vectors by Components Components Magnitude and Angle

September 5, 2005Center for Solar-Terrestrial Research Multiplying Vectors Scalar ProductVector Product

September 5, 2005Center for Solar-Terrestrial Research Questions  How much would a cup of coffee cost at the Cafeteria in (a) Italian Lira and (b) in Euros?  How old are you in seconds?  How long is your way to school in light- years?  How would the introduction of the metric system affect business and daily life in the US?