Physics I (PHY111) Lecture Notes Fall 2024 KSIU

Field of Basic Sciences All Programs Lecture1 : (Physics I (PHY111): Measurements Units and dimensions) Dr. Shehab E. Ali Date : 7/ 10 / 2024 1  Physics I (PHY111) Assessment A...

Field of Basic Sciences All Programs Lecture1 : (Physics I (PHY111): Measurements Units and dimensions) Dr. Shehab E. Ali Date : 7/ 10 / 2024 1  Physics I (PHY111) Assessment Assessment Grade % 10 marks Reports and assignment 10% Final Exam 40 Mid-Term Exam 15 15 marks Mid term exam 15% Course Work 20 20 marks Lecture and lab. works 20% Practical exam 25 15 marks Final Lab. Exam 15% 60% 40 marks Final Exam 40% 100 marks Total 100% Recourses Giambattista, A. (2020). Physics. NY: McGraw-Hill Higher Education. Serway, R. A., Jewett, J. W., & Peroomian, V. (2019). Physics for scientists and engineers. https://www.ekb.eg Course Outline - Units and measurement. - types of motions, - laws of motion, - Applications of Newton’s Laws, - Energy, Momentum and Collisions. - Solids Mechanics: Topics covered include static equilibrium, elasticity, and mechanical properties of solids. - Fluids Mechanics: Topics covered include density, pressure and viscosity, flow and diffusion. - Thermal Physics: includes Temperature, heat and laws of thermodynamics. - Modern Physics: Atomic and nuclear structure of matter; radioactivity: hazard and applications. 2 Introduction 1. Why Study Physics? 2. The Use of Mathematics 3. Scientific Notation and Significant Figures 4. Units 5. Dimensional Analysis 6. Approximation 7. Graphs 4 Physics is The branch of science which deals with nature and natural phenomena. A science that deals with matter and energy and their interactions Why Study Physics? Physics is the foundation of every science (metrology, astronomy, biology, chemistry…). Many pieces of technology and/or medical equipment and procedures are developed with the help of physicists. Studying physics will help you develop good thinking skills, problem solving skills, and give you the background needed to differentiate between science and pseudoscience. 5  Physics and Measurement Physics is based on experimental observations and quantitative measurements. The main objective of physics 1- Find the limited number of fundamental laws that govern natural phenomena , e.g. Gravitation law Electrostatic Law Gas law 2- Use them to develop theories that can predict the results of future experiments. Rotational motion- Coulomb's Law- Magnetic Induction…. etc The fundamental laws used in developing theories are expressed in the language of mathematics, the tool that provides a bridge between theory and experiment.  Physics and Measurement When a discrepancy between theory and experiment arises New theories must be formulated to remove the discrepancy. Many times, a theory is satisfactory only under limited conditions; A more general theory might be satisfactory without such limitations For example, The laws of motion discovered by Isaac Newton (1642–1727) in the 17th century accurately describe the motion of objects moving at normal speeds but do not apply to objects moving at speeds comparable with the speed of light. In contrast, The special theory of relativity developed by Albert Einstein (1879–1955) in the early 1900s gives the same results as Newton’s laws at low speeds but also correctly describes motion at speeds approaching the speed of light. Hence, Einstein’s special theory of relativity is a more general theory of motion. Classical physics includes the theories, concepts, laws, and experiments in classical mechanics, thermodynamics, optics, and electromagnetism developed before 1900. Important contributions to classical physics were provided by Newton, who developed classical mechanics as a systematic theory and was one of the originators of calculus as a mathematical tool. Major developments in mechanics continued in the 18th century, but the fields of thermodynamics and electricity and magnetism were not developed until the latter part of the 19th century, principally because before that time the apparatus for controlled experiments was either too crude or unavailable. Modern physics A major revolution in physics, usually referred to as modern physics, began near the end of the 19th century. Modern physics developed mainly because of the discovery that many physical phenomena could not be explained by classical physics. The two most important developments in this modern era were the theories of relativity and quantum mechanics. Einstein’s theory of relativity 1- not only correctly described the motion of objects moving at speeds comparable to the speed of light 2-but also completely revolutionized the traditional concepts of space, time, and energy. 3- The theory of relativity also shows that the speed of light is the upper limit of the speed of an object and that mass and energy are related. Quantum mechanics was formulated by a number of distinguished scientists to provide descriptions of physical phenomena at the atomic level.  Physics (1600 - 1900) (1900 - now) Classical Modern Physics Mechanics ,Thermodynamics, optics and relativity and quantum electromagnetism mechanics 6 III- Relation of Physics to other fields Electrical Engineering Medicine physics Chemical Mechanical Engineering Engineering 1 1 1-5 Units, Standards and the SI system Physical Quantities 1-Base 2-Derived Quantity Quantity A quantity that must be defined in terms of a standard unit.(Can not be A quantity that is defined in terms defined in terms of other quantities) of base quantities. Base Quantity Base Unit: Unit corresponding to base Derived Unit: unit corresponding to derived quantity quantities. 1- Length meter ≡ m 2- Time second ≡ s Examples: 3- Mass kilogram ≡ kg 4- Electric current ampere ≡ A 1- Speed ≡ Length/Time (Its unit m/s) 5- Temperature kelvin ≡ K 2- Acceleration ≡ Speed/Time 6- Amount of substance mole ≡ mol Lectu re Notes PHY 101 ≡Length/(Time)2 (Its unit m/s2) 7- Luminous intensity candela ≡ cd 5 Dimensions and Units Dimensions are basic types of quantities that can be measured or computed. Examples are length, time, mass, electric current, and temperature. A unit is a standard amount of a dimensional quantity (e.g., meters, seconds, pounds, etc.). There is a need for a standardized international system of units in physics. SI units will be used throughout this class. 12 SI Base Units These units are based on an agreed upon international standard. 13 Prefixes Alternative writing method Using standard form N × 10n where 1  N < 10 and n is an integer This galaxy is about 2.5 × 106 light years The diameter of this atom is about from the Earth. 1 × 10−10 m. 14 prefixes Some of the standard SI unit prefixes and their respective powers of 10: Derived Units A derived unit is composed of combinations of base units. Example: The SI unit of energy is the joule: 1 joule = 1 kg m2/s2 Kilograms (kg), meters (m), and seconds The joule is a derived unit. (s) are base units. 16 Converting Units Units can be freely converted from one to another. Examples: 12 inches = 1 foot 1 inch = 2.54 cm Example: The density of air is 1.3 kg/m3. Change the units to slugs/ft3. 1 slug = 14.59 kg, 1 m = 3.28 feet k g  1 s lu g    3 1 m 1.3 3    3.2 8 feet  = 2.5  1 0 −3 s l u g s / f t 3 m  1 4. 5 9 k g   17 1-6 Converting Units Example 1 A car is moving with 52 mi/h. What its speed in (a) km/h. (b) SI unit. Solution (a) 1 mile = 1.609 km 52 mi /h = 52× 1.609 km/h = 83.67 km/h. 52 mi/h = 83.67 km/h (b) 1 mile = 1609 m , 1h= 60 × 60s = 3600s 52 mi/h = 52 × 1609 m/ 3600s =( 52 × 1609/3600) m/s 52 mi/h = 23.24 m/s PHY 101 Lecture Notes 1 9 The Use of Mathematics x is multiplied by the factor m. The terms y = m x + b mx and b are added together. Proportions A B A is proportional to B. The value of A is directly related to the value of B. A 1 A is proportional to 1/B, or A is inversely proportional to B. The value of A is inversely related to the value of B. B Example A  r 2 A =  r2 The proportionality constant is . 2 A1 2 ( 5 c m ) = r1 2 = Suppose you have one circle with a radius of 5.0 cm and a second circle with a radius of 3.0 cm. 2 = 2.8 A2 r2 (3 cm) The area of the first circle is 2.8 times larger than the second circle. 7 Scientific Notation and Significant Figures Example: The radius of the sun is 700,000 km. In scientific notation, this is written as 7.0105 km. When properly written, the first number will be between 1.0 and 10.0 Example: The radius of a hydrogen atom is 0.0000000000529 m. This is more easily written as 5.2910-11 m. This is a shorthand way of writing very large and/or very small numbers. 8 Figure 1.1 Scientific notation uses powers of ten to express quantities that have a wide range of values. Rules for Identifying Significant Figures (1) Starting with the first non-zero digit on the left. (2) Count the zero in the middle and at the right. (3) In multiplication and division, round to the factor with the fewest significant figures. (4) In addition and subtraction round to least number after decimal point. Examples: i) 0.023070 has five significant figures ii) 0.000072 has two significant figures (7.2 ×10-5) iii) 7.434 × 0.26 = 1.93284 = 1.9 (2 significant figures as 0.26) iv) 44.56005 + 0.0698 + 1103.2 = 1147.82985 ≈ 1147.8 10 Dimensional Analysis Dimensions are basic types of quantities such as length [L]; time [T]; or mass [M]. The square brackets refer to dimensions, not particular units. 18 Dimensional Analysis Example Text problem 1.92: Use dimensional analysis to determine how the period of a pendulum depends on mass, the length of the pendulum, and the acceleration due to gravity (here the units are distance/time2). Mass of the pendulum [M] Length of the pendulum [L] Acceleration of gravity [L/T2] The period of a pendulum is how long it takes to complete 1 swing; the dimensions are time [T]. 19 Solution [L ] [T] = [L]/[T]2 length of pendulum  period  acceleration due to gravity This is essentially done by trial and error. Don’t be afraid of making a mistake. The answer is the square root of [L]/[L/T^2]: We can only conclude that it is proportional. An unknown (unitless) constant of proportionality may be present. 20 Approximation All of the problems that we do in physics are an approximation of reality. We will use models of how things work to compute our desired results. The more effects we include, the more correct our results will be. Often, we can obtain a satisfactory answer by estimating. Example (text problem 1.52): Estimate the number of times a human heart beats during a lifetime. Say a typical heart beats about 60 times per minute, and a lifetime is about 75 years.  6 0 beats   6 0 minutes   2 4 hours   3 6 5 days   7 5 years   1 minute       1 lif e tim e   1 hour   1 day   1 year    = 2.4  1 0 9 beats/lifetime Graphs Experimenters vary a quantity (the independent variable) and measure another quantity (the dependent variable). One graphs the dependent variable (vertical axis) vs. the independent variable (horizontal axis). Dependent variable on vertical axis. Independent variable on horizontal axis. Label Axes Always label the axes with both the quantity and its unit. For example, in a graph of position versus time: Position (meters) Time (seconds) Example Graphing Problem (text problem 1.56) A nurse recorded the values shown in the table for a patient’s temperature. Plot a graph of temperature versus time and find (a) the patient’s temperature at noon, (b) the slope of the graph, and (c) if you would expect the graph to follow the same trend over the next 12 hours? Explain. The given data: Time Decimal time Temp (F) 10:00 AM 10.0 100.00 10:30 AM 10.5 100.45 11:00 AM 11.0 100.90 11:30 AM 11.5 101.35 12:45 PM 12.75 102.48 24 Problem Solution Part 1 103 102.5 102 Temp (F) 101.5 101 100.5 100 99.5 10 10.5 11 11.5 12 12.5 13 Time (hours) Problem Solution Part 2 T − T1 101.8 F −100.0 F b) s l o p e = 2 = = 0.9 F/hr t 2 − t1 12.0 hr −10.0 hr c) No. The patient would not survive such a large temperature increase. a) Reading from the graph: 101.8 F. Summary Measurement SI Units ⚫ Defined by relationships to ⚫ International System of Units base quantities ⚫ Each base unit has an ⚫ Each defined by a standard, accessible standard of and given a unit measurement Changing Units Length ⚫ Use chain-link conversions ⚫ Meter is defined by the distance traveled by light in a ⚫ Write conversion factors as vacuum in a specified time unity interval ⚫ Manipulate units as algebraic quantities Summary Time Mass ⚫ Second is defined in terms of ⚫ Kilogram is defined in terms of oscillations of light emitted by a a platinum-iridium standard cesium-133 source mass ⚫ Atomic clocks are used as the ⚫ Atomic-scale masses are time standard measured in u, defined as mass of a carbon-12 atom Density ⚫ Mass/volume 27