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May st 21 2007 Fundamentals of Physics I PHYS 1501 Course Code 2501 SUMMER 2007 09:00 am – 12:00 noon Physics 1501: FUNDAMENTALS OF PHYSICS I Course Code 2501 • Dr. Tom N. Oder • WBSH 1016, E-mail: [email protected], phone (330) 941-7111 • Website: http://www.ysu.edu/physics/tnoder • Office Hours: M, W, F 12:00 noon – 1:00 pm. • Research: (Wide Band Gap) Semiconductors. Link to Class web page: http://www.ysu.edu/physics/tnoder/X07-PHYS2501/index.html Required Materials (a) Text: College Physics, By A. Giambattista et al., 2nd Edition (b) CPS-RF response pad. (c) Sign up online at www.eInstruction.com. A strong background in algebra (Math 1504 or High school algebra and trigonometry) Hard Cover version YSU Customized version Vol. 1 CPS RF Clickers Location of Serial Number Regular/Punctual Class attendance encouraged. Homework: In the Syllabus, will not be graded. For your practice Quizzes: • Short in-class + Worksheets. No make-ups. • Least three scores will be dropped. Exams No make-ups will be given. Midterm1: Ch.1, 2, 3, 4 on Fri. June 1st. Midterm2: Ch. 5, 6, 7 on Mon. June 11th. Midterm3: Ch.8, 10, 11 on Fri. June 22nd. Finals: Ch. 1-8, 10-12 on Fri. June 29th Exam questions will be developed from questions in the Homework/Quizzes/Worksheets/Class notes. Grading: Quizzes/Worksheets :100 points Midterms (100 points each): 300 points Final Exams: 200 points. Final Grade: 540 – 600 points (90% - 100%) = A 480 – 539 points (80% - 89%) = B 420 – 479 points (70% - 79%) = C 360 – 419 points (60% - 69%) = D 0 – 359 points (0% - 59%) = F No bonus points, no grade-curving Cell Phones: • Cell phones must be turned off during class and exam sessions. •A student whose cell phone audibly goes on during any exam will lose 5% of his/her points in that exam. Chapter 1: INTRODUCTION • Physics: branch of physical science that deals with energy, matter, space and time. • We will use certain words common in everyday speech, but their scientific definition may be completely different from their everyday common meanings. Eg. Velocity, speed, acceleration, work etc. § 1.3: Factor, Proportion: • Factor (or ratio) – number by which a quantity is multiplied or divided when changed from one value to another. • Eg. The volume of a cylinder of radius r and height h is V = r2h. If r is tripled, by what factor will V change? • Vold = r2h, Vnew = (3r)2h = 9. r2h, Vnew/Vold = 9. V will increase by a factor of 9. Proportion • If two quantities change by the same factor, they are directly proportional to each other. • A B – means if A is doubled, B will also double. • S r2 – means if S is decreased by factor 1/3, r2 (not r!) will also decrease by the same factor. Inverse Proportion • If A is inversely proportional to B – means if A is increased by a certain factor, B will also decrease by the same factor. • K inversely proportional to r [K 1/r] – means if r is increased by factor 3, K will decrease by the same factor. § 1.4: Scientific notation: • Rewriting a number as a product of a number between 1 and 10 and a whole number power of ten. • Helps eliminate using too many zeros. • Helps to correctly locate the decimal place when reporting a quantity. • Eg: Radius of earth = 6,380,000 m = 6.38 x 106 m Radius of a hydrogen atom = 0.000 000 000 053 m = 5.3 x 10-11 m. Precision in Scientific Measurements • In reporting a scientific measurement, it is important to indicate the degree of precision in the number. This helps other people to appreciate the accuracy of your measurement. • This can be done using absolute (or percentage) error, significant figures and order of magnitude. (a)Absolute/Percentage error: Eg. Length of a notebook = 27.9 ± 0.2 cm Actual length is somewhere between 27.9 – 0.2 and 27.9+0.2, ie 27.7 and 28.1 cm ± 0.2 is the estimated uncertainty. 0.2 is the absolute uncertainty. 27.9 is the central value 27.7 and 28.1 are called extreme values. Percentage Uncertainty Absolute Value x100 Percentage uncertainty = Central Value Eg. Length of a notebook = 27.9 ± 0.2 cm % Uncertainty = 0.2 x 100 0.7% 27.9 (b) Significant Figures: Number of reliably known digits in a measurement. Includes one “doubtful” or estimated digit written as last digit. Eg. 2586 [6 is the last digit. It is the doubtful digit]. Eg. 25.68 [8 is the last digit. It is the doubtful digit]. Significant Figures contd: • All nonzero digits are significant. • Zeros in between significant figures are significant.[2,508] • Ending zeros written to the right of the decimal point are significant. [0.047100]. • Zeros written immediately on either sides of decimal point for identifying place value are not significant. [0.0258, 0.258] • Zeros written as final digits are ambiguous.[25800] To remove ambiguity, rewrite using scientific notation. • Eg. (i) 58.63 – 4 sf, (ii) 0.0623 – 3 sf, (iii) 5.690 x 105 – 4 sf. (iv) 25800 – 2.58x 104 = 3 sf, 2.580x 104 = 4 sf, 2.5800x 104 = 5 sf. Significant Figures in Addition/Subtraction The sum/difference can not be more precise than the least precise quantities involved. ie, the sum/difference can have only as many decimal places as the quantity with the least number of decimal places. Eg: 1) 50.2861 m + 1832.5 m + 0.893 m = 2) 77.8 kg – 39.45 kg = What is the difference between accuracy and precision? Significant Figures in Multiplication/Division The product/quotient can have only as many sf as the number with the least amount of sf. Eg: 1) What is the product of 50.2861 m and 1832.5 m? 2) What is 568 m divided by 2.5 s? (c) Order of Magnitude – (roughly what power of ten?) To determine the order of magnitude of a number: • Write the number purely as a power of ten. • Numbers < 5 are rounded to 100 • Numbers 5 are rounded to101 • Eg. 754 =7.54 x 102 ~101 x 102 = 103. The order of magnitude of 754 is 3. • 403,179 = 4.03179 x 105 ~100 x 105 = 105 = 5 O/M • 0.00587 ~ orders of magnitude = - 2 (how?). § 1.5: Units We will use the SI system of units which is an international system of units adapted in 1960 by the General Council of Weights and Measures. • In SI system: Length is measured in meters (m). Mass is measured in kilograms (kg). Time is measured in seconds (s). • Other fundamental quantities and their units in the SI system includes Temperature (in Kelvin, K), Electric current (in Amperes, A) Amount of substance (in mole, mol) and Luminosity (in Candela, cd). • The SI system is part of the metric system which is based on the power of ten. Converting Between Units Eg. Convert 65 miles/hour to SI units. 1 mile = 1.609 km = 1609 m. 1 hour = 3,600 seconds 65 miles 65 x 1609m 29.1 m / s 1 hour 1 x 3600 s § 1.6: Dimensional Analysis Dimensions – Units of basic (Fundamental) quantities: Mass [M], Length [L], Time [T] We can only add, subtract or equate quantities with the same dimensions. Eg. 1 Check if the expression v = d2/t is correct, where v = speed (in m/s), d is the distance (in m) and t is time (in s). Quantity Dimension [M ] V [T ] d2 T [M]2 [T] v = d2/t [ M ] [ M ]2 [T ] [T ] Hence eqn is not correct Eg. 2: If the equation was now correctly written as v = kd2/t, what must be the units of k? [M ] [ M ]2 1 k k [T ] [T ] [M ] The units of k must be kg-1 § 1.7-1.9: Reading Assignment