PowerPoint Presentation

1General Physics (PHYS101)

Golibjon Berdiyorov2Golibjon Berdiyorov, Room 148 Physics BuildingPhone: 860-3869/2283e-mail: golib@kfupm.edu.sa www.cmt.ua.ac.be/golib/PHYS101Syllabus and teaching strategyLecturer:Sunday: 3.20pm-4.10pm (6/125) 25-27Tuesday: 3.20pm-4.10pm (6/125) 25-27Thursday: 3.20pm-4.10pm (6/125) 25-27Office Hours:Sunday-Thursday: 8.00-10.00 Lectures:Recitation:Monday: 1.10pm-2.00pm (6/209) 25 3.20pm-4.10pm (6/165) 26 4.20pm-5.10pm (6/201) 273Assessment: Grading

DN grade:3 or more unexcused absences in the LAB12 unexcused absences in lecture+recitation

4Warm up for lectures:Read the text(use a highlighter, if you prefer)

Understanding physics (lectures):Answer questions in classBring lecture notes, textbook

Challenge yourself (homework):Homework

Play with physics (lab):Discover with hands-on experience Format for Active Learning

Practice, practice and practice!!!

5Units, Changing units, Significant figuresLecture 01 (Chap. 1, Sec. 1-3)6Physics is based on measurement of physical quantities

1 nanometre =1.0 10-9m

1 light year =9.41015mMeasurementsExamples are: length, mass, time, electric current, magnetic field, temperature, pressure ...All physical quantities have dimensions: dimensions are basic types of quantities that can be measured or computed. 7These quantities are the basic dimensions: Length[L]Mass [M]Time [T] Other physical quantities are defined in terms of these base quantities:- [velocity] = [length]/[time] = [L]/[T]- [volume]=[length]3=[L]3- [density]=[mass]/[volume]=[M]/[L]3 - [force] = [mass][length] /[time]2 = [M][L]/[T]2 Base dimensions8A unit is a standard amount of a dimensional quantity.US customary [L]:1 ft = 0.3048 m1 mile = 1.6 kmA single unified system of units makes life easier!Units can be chosen for convenience:Science [L]:1 angstrom =1.0 10-10metres1 light year =9.4605284 1015metresUnits for physical quantities12 inches in a foot, three feet in a yardInternational System of Units(metric system)Basic SI Units Length meter m Time seconds s Mass kilogram kg Electrical current ampere A Temperature Kelvin K Luminous intensity candela cd Amount of substance mole mol These are the only units necessary to describe any quantity.10 [Area] = m2 square meter [Volume] = m3 cubic meter [Density] = kg/m3 kilogram per cubic meter [Speed] = m/s meter per second [Acceleration] = m/s2 meter per second squared [Force]: N (Newton) = kg m/s2 [Frequency]: Hz (Hertz) = s-1 [Pressure]: Pa (Pascal) = N/m2 [Energy]: J (Joule) = N m [Power]: W (Watt) = J/sLength [L] mTime [T] sMass [M] kgSi derived units11One can measure the same quantity in different units. For instance distance can be measured in miles, kilometres, meters etc. Velocity can be measured in km/hour, m/s etc.

vman-ground= 5km/h + 10 m/s = 15?? -No10 m/s = 36 km/h vman-ground= 5 km/h + 36 km/h = 41 km/hConversion of UnitsIf physical quantities are measured in different units, then they should be converted to the same units. 12Conversion of Units: Chain-link methodExample 1: Express 3 min in seconds?1min = 60 sConversion Factor?Example 2: How many centimeters are there in 5.30 inches?13Conversion of Units1 km = 0.6 milesExample 4: Express 200 km/h in m/s?Example 5: Express 16 m/s in km/h?km/h --> m/s :3.6m/s --> km/h x3.6 1h = 60 min = 60 x 60 s = 3600 sExample 3: Express 200 km/h in miles/s?200 km/h= 200 x 0.6 miles/3600 s = 0.03 miles/s1 km = 1000 m1 h = 3600 s200 km/h= 200 x 1000 m/3600 s = 55.56 m/s1 m = (1/1000) km1 s = (1/3600) h16 m/s= 16 x (1/1000) km/(1/3600) h = 16x3600/1000 km/h=57.6 km/h14Scientific notationExpanded form1 x 10011 x 101101 x 1021001 x 10310001 x 1061 000 0001 x 10-11/10 or 0.11 x 10-31/1000 or 0.0011 x 10-60. 000 001101 = 1.01 x 1024321 = 4.321 x 1031.23 = 1.23 x 1000.25 = 2.5 x 10-10.0007925 = 7.925 x 10-4384000 km=3.84 x 105 km

384000 km

0.0000013 m0.0000013 m=1.3 x 10-6 m

Can we write them in a compact form?

Scientific notationsPrefixes and NotationThe following prefixes indicate multiples of a unit.MultiplierPrefixSymbol1012teraT109gigaG106megaM103kilok10-3millim10-6micro10-9nanon10-12picop10-15femtof16Speed of light: c=299 792 458 m/sc=2.99 792 458 x 108 m/sUnderestimation: the following digits can just be dropped from the decimal place: 0, 1, 2, 3, an 4.

RoundingExample 1. Round c to a nearest 1000th. Overestimation: digits 5 to 9 can be dropped from the decimal place during the rounding, however, one should be added to the digit in front of it. c=2.998 x 108 m/s. Example 2. Round c to a nearest 10th. c=3.0 x 108 m/s. Example 3. Round 273.587 to a nearest integer. 274Example 4. Round 273.587 to 2 significant figures. 27017Order of magnitudeAn order of magnitude calculation is a rough estimate that is accurate to within a factor of about 10.It is useful if you want to get a quick rough answer.The order of magnitude of a quantity is the power of ten when quantity is expressed in scientific notationA=7 600 = 7.6 x 103 The order of magnitude of A is 3B=3 700 = 3.7 x 103 The order of magnitude of B is 3A=7 600 ~ 10 000 = 104 The nearest order of magnitude of A is 4B=3 700 ~ 1 000 = 103 The nearest order of magnitude of B is 318Uncertainties in measurementsAll measurements are subject to an uncertaintyThese uncertainties can be due to e.g. limitations in the measuring tools or fluctuations in the measured quantities.

The accuracy of the measurements are determined by significant figures.

19Rules for Significant Figures1. All nonzero figures are significant 359 87678 1245 987889 2. All zeros between nonzeros are significant 205 1003 508009 800009002 3. Zeros at the end are significant if there is a decimal point before them 4.200 1003.5600 30.003000 4. All other zeros are non-significant 30000 0.0000344 20Rules for Significant Figures0 . 0 0 4 0 0 4 5 0 0 Not significantzero at the beginningNot significantzero used only to locate the decimal pointSignificantall zeros between nonzero numbersSignificantall nonzerosintegersSignificantzeros at the end ofa number to the rightof the decimal point

Just take care of zeros21Operations with Significant FiguresWhen adding or subtracting, round the results to the smallest number of decimal places of any term in the sum

22Operations with Significant FiguresWhen multiplying or dividing, round the result to the same accuracy as the least accurate measurements (i.e. the smallest number of the significant figures)Example: Calculate the surface area of a plate with dimensions 4.5 cm by 7.32 cm.A=4.5 cm x 7.32 cm=32.94 cm2.A=33 cm2.Dimensions are basic types of quantities that can be measured or computed.

Base dimensions are length, time, and mass.

A unit is a standard amount of a dimensional quantity. Summary24SummaryScientific notations

RoundingOrder of magnitude: 10x (x=1,2,3 ..)

25SummaryUncertainties in the measurementsIt is important to control the number of digits or significant figures in the measurements. Significant figures

Express the following numbers in scientific notations:a) 0.015b) 0.0000002 c) 54800a) 1.5 x 10-2 b) 2 x 10-7 c) 5.48 x 104Express speed of sound (330 m/s) in miles/h (1 mile = 1609 m)738 miles/h730 miles/h1 shake = 10-8 sec. Find out how many nano seconds (ns) are there in 1 shake (1ns=10-9s).1 ns10 ns