Physics 231 non calculus introductory physics I Section 003 http www pa msu edu people yuan classes htm http www pa msu edu people yuan classes htm C P Yuan yuan pa msu edu Office Hours Mon 11 30AM 12 30PM in 3213 BPS or by y appo appointment ntm nt PHY 231 PHYSICS 231 Lecture 1 Units Measurement Dimension This could be the discovery of the century depending of course on how far it goes down PHY 231 2 Why Make No Mistake Medical Errors Can Be Deadly y Serious The American Hospital Association lists these as some common types of medication errors incomplete patient information unavailable drug information miscommunication of drug orders orders which can involve poor handwriting confusion between drugs with similar names misuse of zeroes and decimal points confusion of f metric i and d other h d dosing i units i and d inappropriate i i abbreviations PHY 231 3 What is a meter Early 18th Century Length of pendulum with half length of 1s Distance from N pole to Equator via Paris 107 1791 second was chosen and 1874 Alloy was made 1889 more precise by using Platinum Iridium Alloy 1960 Using wavelength by using Krypton86 radiation di ti 1983 distance traveled by light in vacuum in 1 299792458 s PHY 231 4 What is a second Originally 1 86400 of a mean solar day 1960 based on a tropical year 1967 9192631770 periods of radiation corresponding to the transition between two hyperfine states of the ground state of 133Cesium PHY 231 5 What is a kilogram End of 18th century 10 3 m3 of water 1889 defined to a Platinum Iridium weight PHY 231 6 Syst me Internationale SI 7 Base B s Units We W will ill us use th them m Quantity Name unit l th length meter t m mass kilogram kg time second electrical Current Ampere A temperature Kelvin amount of substance mole s K Examples mp of f Derived units Speed S d m s Acceleration m s2 Force kg m s kg m s2 N mol Luminous intensity candela cd NIST http physics nist gov cuu index html PHY 231 7 Building blocks and scale 10 f fm nucleus 500 500 nm eye 1 nm crystal 1 fm nucleon 0 1 nm atom 0 01 0 01 fm quarks gluons PHY 231 8 Our solar system Sun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto in miles 0 miles 3 6 107 6 7 107 9 3 10 9 3 107 1 4 108 4 8 108 8 9 108 1 8 109 2 8 10 2 8 109 3 7 109 Simplify 0 0 3 6 6 7 93 9 3 14 1 48 4 88 7 178 6 280 0 280 0 366 4 PHY 231 In the unit of 107 miles 9 Dimensional Analysis Dimension should be treated as algebraic quantities x x0 at 2 2 Correct dimensionally y m m m s 2 s 2 YES Think about u u unit conversions X X0 in ft a in m s2 ft ft m s 2 s 2 1 m 3 281 ft ft ft ft s 2 s 2 YES GOOD W WAY Y TO CHECK IN N EXAMS EX M LIFE L FE PHY 231 10 Uncertainty Significance 1 2411 trillion digits known 3 1415926535 3 59 6535 8979323846 89793 38 6 2643383279 6 3383 79 50 5028841971 88 97 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 8214808651 3282306647 0938446095 5058223172 5359408128 4811174502 8410270193 8521105559 6446229489 5493038196 PHY 231 11 Significance Uncertainty Circumference 2 R 2 3 1415926 4 2 Calculator 26 26 38937 38937 m Right answer 26 m R 4 2 m 4 2 means that the true value lies between 4 1 and 4 3 2 4 1 25 761 26 m 2 4 1 25 761 26 2 4 3 27 0176 27 m so Right Answer with error 26 1 The number of significant figures for a result of a division or multiplication is the least accurate of the quantities being divided or multiplied multiplied PHY 231 12 Significance Uncertainty For addition and subtraction the number of decimal places should be equal to the smallest number of d i l places decimal l of f any tterm iin th the sum 3 0001 0 0025 3 0001 0 0025 3 3 0026 0026 NUMBER OF DECIMAL PLACES IS NOT THE SAME AS THE NUMBER OF SIGNIFICANT FIGURES 0 0025 2 significant figures 4 decimal places Scientific notation For example 7 107 or 7E 07 PHY 231 13 Coordinate Systems r b Cartesian Coordinates x y a b Plane polar coordinates r a r a b 2 Frame transformation 2 tan b a PHY 231 14 TRIGONOMETRY SOH CAH TOA sin opposite hypotenuse h cos adjacent hypotenuse tan opposite adjacent pp j Pythagorean theorem c a b 2 2 2 Note that sin cos tan are dimensionless 2 radians corresponds to 360o PHY 231 15 How to solve a problem READ THE PROBLEM If you have a problem understanding what is asked try to visualize it in a simpler system or in a comparable situation that you are familiar with Determine what is known and how these quantities relate to the unknown How do you combine the givens to find the unknown dimensional analysis can help h l Take care of the units Calculate the unknown unknown taking care of significance and decimal places Check whether your answer makes sense PHY 231 16 Problem The diameter of the orbit of the earth around the sun is 4x1011 m m 1 What is the distance traveled by the earth in 1 year 2 in the polar coord System with the sun in the center over what h t angle l does d the th earth th travel t l in i 0 30 0 30 year 1 a 1x1012 m 2 a 108 degrees b 2x1012 m b 120 degrees g c 2 5x1012 m c 1 88 radians d 1 3x1023 m d 1 1x102 degrees PHY 231 17
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