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  • 1. HigH ScHool Science Today FourTH year Textbook
  • 2. HigH ScHool Science TodayFourth YearTextbookPhilippine Copyright 2009 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the PhilippinesEditorial, design, and layout by University Press of First AsiaNo part of this publication may be reproduced or transmitted in any form or by any meanselectronic or mechanical, including photocopying, recording, or any information storage andretrieval systems, without permission in writing from the copyright owner. Exclusively distributed by DIWA LEARNING SYSTEMS INC 4/F SEDCCO 1 Bldg. 120 Thailand corner Legazpi Streets Legaspi Village, 1229 Makati City, Philippines Tel. No.: (632) 893-8501 * Fax: (632) 817-8700 ISBN 978-971-46-0103-1reviewerBhazel Anne H. Rara-Pelicano has a bachelor’s and master’s degree in Physics from theUniversity of the Philippines–Diliman. She is currently pursuing her doctorate degree in Physicsin the same university. She has received awards and scholarships in the field of physics. Ms. Rara-Pelicano is an instructor of the National Institute of Physics at the University of the Philippines–Diliman.
  • 3. P r e Fa c e Discoveries in science and technology in recent years have had a profound impact onour society. We are now able to communicate easier with the use of the Internet and cellularphones. We have found ways to replace damaged body parts through prostheses and organtransplants. People are continually developing new medicines to treat diseases that wereonce fatal. Scientists have been able to clone animals, find alternative fuel sources, explorethe far reaches of outer space, and develop better materials for construction. Even the waywe entertain ourselves has been affected by discoveries in science. With all these fascinating discoveries, it is important that you understand thescientific principles behind such advancements. The High School Science Today series hasbeen developed with two objectives in mind: to explain key scientific concepts clearly andaccurately within a context of unifying themes; and to introduce you to the technology andresearch techniques which have resulted from the application of these scientific concepts. The topics in each textbook are organized to keep key science concepts in clear view.In each chapter, you will find discussions on specific technological breakthroughs and theimplications these developments have on our global community. Understanding science requires that you observe the things around you, performexperiments to solve problems, and explain the reasons for your observation. Eachtextbook contains activities that will help you develop the skills necessary in learningscience concepts meaningfully. These activities will provide you with hands-on learningexperiences. You will be asked to predict, hypothesize, describe, make models, formconclusions, calculate, and measure with accuracy and precision. As such, High School Science Today will enable you to keep pace with the ever-evolving world of science and technology. We invite you to take this journey with us—intothe future and beyond.
  • 4. Table oF conTenTSuniT 1 energy in SocieTyChapter 1 An Introduction to Physics1.1 Physics throughout Time .................................................................................... 21.2 Major Branches of Physics................................................................................... 41.3 Physicists and Their Attitudes ............................................................................ 71.4 Mathematics in Physics ....................................................................................... 11Chapter 2 Physics, Technology, and Society2.1 Physics and Technology in Daily Life .................................................................. 192.2 Energy and Society .............................................................................................. 23uniT 2 energy and THe environmenTChapter 3 Light as a Wave3.1 Wave and Its Characteristics ............................................................................... 303.2 Reflection ............................................................................................................. 343.3 Refraction ............................................................................................................. 403.4 Diffraction ............................................................................................................ 463.5 Interference .......................................................................................................... 483.6 Polarization .......................................................................................................... 49Chapter 4 Light and Vision4.1 How You See ......................................................................................................... 524.2 Eye Defects and Lenses........................................................................................ 604.3 The Eye and the Camera: A Comparison ............................................................. 634.4 Other Optical Instruments ................................................................................. 65Chapter 5 Atomic Structure and Radioactivity5.1 Atomic Physics ..................................................................................................... 705.2 Nuclear Physics .................................................................................................... 745.3 Matter-Energy Equivalence ................................................................................. 785.4 Nuclear Reactions ................................................................................................ 82Chapter 6 Uses of Nuclear Radiation in Society6.1 Effects of Nuclear Applications ........................................................................... 866.2 Uses of Radioisotopes .......................................................................................... 926.3 Radiation Safety ................................................................................................... 99uniT 3 energy in THe HomeChapter 7 Discovery of Electricity7.1 The Discovery of Electricity ................................................................................. 1067.2 Filipinos in the Field of Electricity ...................................................................... 112
  • 5. Chapter 8 Electrical Circuits8.1 Basic Parts of a Circuit ......................................................................................... 1158.2 Electromotive Force, Current, and Resistance in a Circuit ................................ 1178.3 Types of Electrical Circuit Connection ............................................................... 1208.4 Transfer of Energy in Electrical Appliances ....................................................... 128Chapter 9 Electrical Energy9.1 Measure of Electrical Consumption.................................................................... 1319.2 Electrical Conservation ....................................................................................... 1369.3 Electrical Safety.................................................................................................... 140uniT 4 energy and THe economyChapter 10 Energy Generation, Utilization, Management, and Conservation10.1 Energy Resources and Development in the Philippines .................................... 14610.2 Risks of Energy Development ............................................................................. 156Chapter 11 Electricity and Magnetism11.1 Magnetic Field...................................................................................................... 16211.2 Electromagnetic Induction .................................................................................. 16811.3 Generators and Transformers ............................................................................. 17111.4 Motor .................................................................................................................... 17511.5 Electrical Energy Generation, Transmission, and Distribution ........................ 178uniT 5 energy in TranSPorTaTionChapter 12 Development of Transportation Technology12.1 Transportation: Past to Present .......................................................................... 18812.2 Modes of Transportation .................................................................................... 18912.3 The Future of Transportation.............................................................................. 196Chapter 13 Force and Motion: Applications in Land, Air, and Sea Transport13.1 The Study of Motion ............................................................................................ 20013.2 Newton’s Laws of Motion .................................................................................... 20913.3 Law of Conservation of Momentum ................................................................... 22013.4 Pressure ................................................................................................................ 228Chapter 14 Interrelationship of Force, Power, Work, and Energy14.1 Work, Kinetic Energy, and Potential Energy ..................................................... 24314.2 Conservation of Mechanical Energy ................................................................... 25214.3 Power .................................................................................................................... 25814.4 Machines .............................................................................................................. 26114.5 Temperature ......................................................................................................... 26514.6 Mechanical Equivalent of Heat ........................................................................... 26914.7 Expansion of Solids, Liquids, and Gases............................................................. 27014.8 Specific Heat Capacity.......................................................................................... 27614.9 Heat of Vaporization and Heat of Fusion ........................................................... 27914.10 The Laws of Thermodynamics ............................................................................. 283
  • 6. uniT 6 energy in icTChapter 15 Sound and the Development of Communication15.1 Production of Sound ............................................................................................ 29615.2 Vibration and Waves ............................................................................................ 29715.3 Characteristics of Sound Waves .......................................................................... 29815.4 Doppler Effect ...................................................................................................... 30215.5 Standing Waves .................................................................................................... 30615.6 Energy Transfer and Transformation in Communication ................................. 30715.7 Development of Telecommunication .................................................................. 310Chapter 16 Electromagnetic Theory16.1 Producing Electromagnetic Waves ...................................................................... 31816.2 Electromagnetic Spectrum .................................................................................. 32116.3 Radio Waves in Focus .......................................................................................... 32716.4 Laser and Fiber Optics ......................................................................................... 329Chapter 17 Electronic Components17.1 More on Resistors ................................................................................................ 33517.2 Capacitor .............................................................................................................. 33617.3 Conductors, Semiconductors, and Insulators .................................................... 34317.4 Semiconductor Diodes ......................................................................................... 34917.5 Transistors ........................................................................................................... 35417.6 Simple Integrated Circuits................................................................................... 35817.7 Logic Circuits ....................................................................................................... 360Glossary .............................................................................................................................. 371Bibliography .............................................................................................................................. 375Index .............................................................................................................................. 376
  • 7. Unit 1EnErgy in SociEty Physics is considered a basic science. It deals with universal laws and the study of thebehavior and relationships of physical phenomena. In addition to its intrinsic beauty, physicsalso leads to an understanding of many practical applications and ideas in other areas of science.The laws of physics govern many principles of chemistry, biology, astronomy, and geology, amongothers. The concepts and principles of physics constitute a major foundation of technology.Significant technological developments have been made possible through physics. For example,applications of physics in engineering and medicine have improved the quality of life. Physicsaffects our daily lives in more ways than one.
  • 8. Chapter 1 An introduction to PhySicS Imagine a world without telephones, televisions, and computers. How would peoplecommunicate with one another and acquire information? Achievements in modernscience and technology have made life more convenient for people. As a result, peoplecan communicate regardless of distance, order food and pay bills over the phone, sendmessages electronically, and even replace a damaged internal organ. Many tools, processes, and products have been invented and enhanced throughscientific research and discoveries. Technology refers to the practical application of scienceupon which it is based. It is present in all sectors of society. The pace of technologicalprogress and innovation has reached such tremendous heights that one could wonder ifsociety can cope with these technological changes. It is important that you understand thesignificance or relevance of technological developments and breakthroughs in your daily life. 1. PhySicS throughout timE 1 Physics is the study of the basic interactions of matter and energy and theirtransformations. It is the study of the foundations of the universe from the macroscopiclevel (such as the universe itself) to the microscopic level (like atoms and subatomicparticles). It also provides the framework in the study of other sciences. For example,physics does not teach which atoms combine to form specific compounds, but it explainswhy atoms behave the way they do. The study of physics can be very holistic, but you willfind that many explorations on specific concepts of physics can and has led to very practicalapplications. High School Science Today IV
  • 9. The expansion of physics has brought not only changes in ideas and acquisitions of new ones, but also a transformation of society. Science began even before the first account of history was ever written. People learned to make predictions when they discovered patterns, regularities, and relationships in nature. In the early part of the 17th century, Galileo Galilei agreed with the Copernican view that Earth movedFig. 1.1 Development in the study of various sciences leads to the improvement of life around the sun. He also debunked Aristotle’s falling-body hypothesis. Galileo disproved the long accepted theory of Aristotle, which states that heavy objectswould fall or accelerate faster than light objects. Galileo found out through his experimentsthat objects of different weights, when released at the same time and at the same elevation,would fall and hit the ground at the same time, except when air resistance is present. Oneof his experiments included rolling balls of various weights down an incline. According tolegend, Galileo dropped two cannon balls from the Tower of Pisa to test his hypothesis. At the end of the 17th century, Sir Isaac Newton made a remarkable achievement inphysics when he formulated the laws of motion and gravitation. During the 18th and the 19th centuries, electricity and magnetism were studied.In 1819, Hans Christian Oersted of Denmark discovered that a compass needle canbe deflected by a current-carrying wire. Andre Ampere of France carried out a similarinvestigation and proved the same. A few years later, Michael Faraday of England andJoseph Henry of the United States of America further validated that electricity andmagnetism are indeed related. It was during this time that James Clerk Maxwell relatedelectricity and magnetism in one coherent theory. The nature of light as an electromagneticwave was explained by Heinrich Hertz. At the beginning of the 20th century, Albert Einstein’s development of the theoryof relativity and his ideas on quantum mechanics marked a historic milestone in physics.Einstein’s theory of special relativity tells the nature of objects traveling at or near thespeed of light, while quantum mechanics studies the behavior of subatomic particles suchas electrons. Energy in Society
  • 10. 1.2 mAjor BrAnchES of PhySicS During Einstein’s time, all fields of science were developing rapidly and their linkto physics was established. Scientists realized that there had been overlaps between thedifferent fields of science. Chemists and astronomers had to be knowledgeable aboutphysics. Biologists had to be familiar with chemistry and physics. The integration ofastronomy, chemistry, geology, and biology to physics thus became necessary. The following are the major branches of physics:• Astrophysics. This branch of physics deals with the physical and chemical nature of celestial objects and events. It has sometimes been defined as the application of physical laws concerning astronomical objects. Astrophysics applies the theories and methods of physics to the study of stellar structure and evolution—the origin of the solar system.• Physical chemistry. This branch of physics combines the principles and methods of physics and chemistry. The fundamental, theoretical, and experimental basis of organic, inorganic, and analytical chemistry is provided by the principles of physical chemistry. It is also the foundation of chemical engineering. Physical chemistry focuses on the study of chemical equilibrium, reaction rates, solutions, molecular weights and structure, and the properties of gases, liquids, and colloids. This field considers the influence of turbulence of fluids, temperature, pressure, electricity, and light. There are three principal approaches involved in physical chemistry. Thermodynamics involves large numbers of molecules in equilibrium. Kinetics involves chemical changes in relation to time. Molecular structure involves the electronic and atomic arrangements in which the quantum theory is applied.• Geophysics. This is the study of the structure, composition, and dynamic changes of Earth, its lithosphere, hydrosphere, atmosphere, and magnetosphere based on the principles of physics. Some principles of geophysics are applied in locating subsurface Fig. 1.2 Application of geophysics in finding subsurface petroleum and other mineral deposits petroleum, mineral deposits, High School Science Today IV
  • 11. and water supplies. Geophysics is also used to understand the interactions of the atmosphere and hydrosphere and how certain anomalies in the ocean’s circulation affect the atmosphere. Geophysics also explains the relation of the layers of the lithosphere to the amount and kind of subsurface water.• Biophysics. This refers to the application of various methods and principles of physical science to the study of biological problems. It has branched out to different major divisions. In physiological biophysics, physical mechanism is used to explain biological processes such as the transmission of the nerve impulses, the muscle contraction mechanism, and the visual mechanism. Theoretical biophysics, on the other hand, tries to use mathematical and physical models to explain life processes. Radiation biophysics studies the response of organisms to various kinds of radiation for diagnostic and treatment purposes. Medical physics is the application of concepts and methods of physics to medicine, specifically, to diagnose and treat or cure human diseases. The principles of biophysics are applied in the study of organic molecules, which play an important part in the biological processes. Paper chromatography, a direct development of adsorption techniques, is widely used to analyze tissues for chemical components. X-ray crystallography, on the other hand, is used to determine molecular structures. It has also been useful in studying the complex structure of proteins. lid paper solvent front solvent (a) (b) Fig. 1.3 (a) Paper chromatography and (b) X-ray crystallography The study of biological problems requires optical methods. Among these optical methods are photochemistry, light scattering, absorption spectroscopy, and laser beams. These methods allow biophysicists to determine the structure of molecules in plants and animals to a degree not readily possible with ordinary chemical methods. Energy in Society
  • 12. The following are the other branches of physics.• Atomic physics. This is the study of the properties and structure of atoms and the forces that act between the positive nuclei and the negative electrons in orbit around the nuclei.• Electrodynamics. This is the study of the interactions between electric currents and magnetic fields created by other electric currents.• High energy physics or particle physics. This is the study of the structure, properties, and interactions of elementary particles.• Mechanics. This is the study of the behavior of physical systems in terms of their position in space, under the action of external forces which may be equal to or different from zero.• Nuclear physics. This is the study of the structure of atomic nuclei and the forces responsible for the stability or the degradation of atomic nuclei and their relation to the formation of nuclear energy.• Optics. This is the study of the phenomena associated with the generation, transmission, and detection of electromagnetic radiation. Optics also studies light and vision.• Thermodynamics. This is the study of the mechanical properties of matter related to energy transformations involving heat and mechanical work and how it affects matter. ACTIVITY Physics and Other Sciences Materials small pieces of paper with the following labels: biophysics, astrophysics, physical chemistry, geophysics, role-playing, song writing, panel discussion, and games Procedure 1. The labels will be categorized into A and B. A should include biophysics, astrophysics, physical chemistry, and geophysics, and B should contain role- playing, song writing, panel discussion, and games. 2. The class will be divided into four groups and a representative from each group will be chosen. 3. Each representative should pick one piece of paper from A and another from B. 4. Labels from B will be the activity to be completed by the group, and labels from A will be the topic. For example, the group which has picked biophysics and role-playing should perform a role-playing activity about biophysics. 5. Each group should present its activity to the class. High School Science Today IV
  • 13. Why is it important to be knowledgeable in physics if one is to study astronomy, biology, geology, or chemistry? Understanding the principles of physics and its applications in other fields will help you cope with the demands of today’s highly technological world. Recent developments in the field of optoelectronics, lasers, and alternative sources of energy show the practical and useful applications of the principles of physics. 1.3 PhySiciStS And thEir AttitudES Physicists must possess scientific attitudes that can be used in their continuous searchfor knowledge about how and why things behave under different conditions. Attitudesinfluence a physicist’s way of thinking and his/her actions. These attitudes are ways oflooking at things developed through years of experience. Physicists should be creative and curious. They make accurate observations and havethe capacity to design experiments and develop hypotheses and models. They are alsowilling to suspend judgment until they have proven a hypothesis to be true. They are honestin reporting data and observations they have gathered. Physicists combine curiosity andimagination to obtain answers by experimentation. Physicists carefully study and validate observations instead of disputing themright away. However, among physicists themselves and other scientists for that matter,interpretation of certain observations may differ. Physicists are open-minded. They are willing to accept new ideas and try them out.They are also critical. They analyze and investigate the accuracy of new ideas beforeaccepting them fully. These positive attitudes enabled the scientific giants—Galileo, Newton, and Einstein—to discover scientific principles that improved and continues to improve human life. Today’sphysicists also possess these attitudes. It allows them to help mankind and improve thequality of life. Who are some of these physicists and what aretheir contributions to the modern world?Filipino Physicists Gregorio Y. Zara, D. Sc. Physics. His importantcontributions include the invention of the two-way televisiontelephone, the invention of an airplane engine that runs onalcohol, and other methods by which solar energy can beharnessed. Fig. 1. Gregorio Y. Zara Energy in Society
  • 14. In 1930, he discovered a basic physical law—the law of kinetic electrical resistance orthe Zara effect. The law states: “All contacts, turning or sliding, between metals, between carbon and metals, betweenmetals and mercury, or between conductors, produce a resistance to the passage of electric currentwhich may be kinetic and/or permanent electrical resistance. This is observed at currents of verylow amperage. Kinetic electrical resistance is the resistance to the passage of electric current whencontacts are in motion. Permanent electrical resistance manifests itself when contacts are at rest.” Engr. Diosdado ‘Dado’ Banatao. His advanced chipdesigns were among the information technology (IT) productsthat helped popularize the California Silicon Valley. This chipdesign became the basic building blocks of the three high-techcompanies he started. Among his companies are the following:Mostron, Inc., a successful manufacturer of PC motherboards;Chips and Technologies, a developer of chip-sets; and SiliconSubSystems or S3, a pioneer of the world’s first single-chipgraphic user interface (GUI) accelerator. The GUI acceleratoreliminates the bottleneck of the graphics subsystem, thusimproving performance of computers. He has been acclaimed for having developed the first-ever Fig. 1. Diosdado BanataoEthernet controller chip that has enabled computers to linkup and communicate with one another. This controller chip is designed to simplify thecomplexity of the personal computer. Banatao was awarded the Distinguished Leadership Award by the Asian BusinessLeague, Entrepreneur Award by the Inc. Magazine, and the Ellis Island Medal of Valor bythe National Ethnic Coalition of Organizations. Amador Muriel, Ph.D. He developed a theory addressing the turbulence observedin fluids. This theory of turbulence considers the individual molecules in the fluid. It isnow being tested and examined in laboratories in France,Russia, United States, Taiwan, and Hong Kong. If the theoryis proven and given practical applications, airline disasters andair disturbances would decrease and safety in air travel wouldbe ensured. Also, understanding how turbulence works wouldreduce airline fuel costs by billions of dollars annually. For these breakthroughs, Muriel has been recognizedby the international scientific community. He was appointedmember of the Institute for Advanced Studies in Princeton in1997. In 1999, he was chosen as one of the Ten Outstanding Fig. 1. Amador MurielFilipinos in Science. High School Science Today IV
  • 15. Foreign Physicists Table 1.1 shows the list of the Nobel Prize Winners for physics from 1990 to2008. Alfred Nobel, the scientist who invented dynamite in 1866, built companies andlaboratories in more than 20 countries all over the world. He held more than 350 patentsand even wrote poetry and drama. Nobel shared his fortune through the Nobel Foundationwhich he established at the beginning of the 20th century. The Nobel Prize is acknowledgedas the most prestigious and the highest form of international recognition in the fieldsof physics, chemistry, medicine, literature, peace, and economics. The Nobel Foundationcelebrated its 100th anniversary on 29 June 2000.Table 1.1 Nobel Prize Winners for Physics from 1990 to 2008 Year Recipients Contribution Yoichiro Nambu for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics 2008 Makoto Kobayashi for the discovery of the origin of the broken symmetry Toshihide Maskawa which predicts the existence of at least three families of quarks in nature Albert Fert for the discovery of Giant Magnetoresistance 2007 Peter Grünberg John C. Mather for their discovery of the blackbody form and 2006 George F. Smoot anisotropy of the cosmic microwave background radiation Roy J. Glauber for his contribution to the quantum theory of optical coherence 2005 John L. Hall for their contributions to the development of laser- Theodor W. Hänsch based precision spectroscopy, including the optical frequency comb technique David J. Gross for the discovery of asymptotic freedom in the theory 2004 H. David Politzer of the strong interaction Frank Wilczek Alexei A. Abrikosov for pioneering contributions to the theory of 2003 Vitaly L. Ginzburg superconductors and superfluids Anthony J. Leggett Raymond Davis Jr. for pioneering contributions to astrophysics, in Masatoshi Koshiba particular for the detection of cosmic neutrinos 2002 Riccardo Giacconi for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources Energy in Society
  • 16. Eric A. Cornell for the achievement of Bose-Einstein condensation in 2001 Wolfgang Ketterle dilute gases of alkali atoms, and for early fundamental Carl E. Wieman studies of the properties of the condensates Zhores I. Alferov for developing semiconductor heterostructures used in 2000 Herbert Kroemer high-speed- and opto-electronics Jack S. Kilby for his part in the invention of the integrated circuit Gerardus ‘t Hooft for elucidating the quantum structure of electroweak 1999 Martinus J.G. Veltman interactions in physics Robert B. Laughlin for their discovery of a new form of quantum fluid with 1998 Horst L. Störmer fractionally charged excitations Daniel C. Tsui Steven Chu for the development of methods to cool and trap atoms 1997 Claude Cohen-Tannoudji with laser light William D. Phillips David M. Lee for their discovery of superfluidity in helium-3 1996 Douglas D. Osheroff Robert C. Richardson Martin L. Perl the discovery of the tau lepton 1995 Frederick Reines the detection of the neutrino Bertram N. Brockhouse for the development of neutron spectroscopy 1994 Clifford G. Shull for the development of the neutron diffraction technique Russell A. Hulse for the discovery of a new type of pulsar, a discovery 1993 Joseph H. Taylor Jr. that has opened up new possibilities in the study of gravitation Georges Charpak for his invention and development of particle detectors, 1992 in particular the multiwire proportional chamber Pierre-Gilles de Gennes for discovering that methods developed for studying order phenomena in simple systems can be generalized 1991 to more complex forms of matter, in particular to liquid crystals and polymers Jerome I. Friedman for their pioneering investigations concerning deep Henry W. Kendall inelastic scattering of electrons on protons and bound 1990 Richard E. Taylor neutrons, which have been of essential importance for the development of the quark model in particle physicsSource: Nobel Laureates in Physics (http://nobelprize.org/nobel_prizes/physics/laureates) These people have made remarkable leaps in the realm of physics. Their discoveries ledto inventions and innovations which have improved and are continuously improving ourworld.10 High School Science Today IV
  • 17. 1.4 mAthEmAticS in PhySicS Physics is a science that can show relationships between and among quantities. Theserelationships are expressed using mathematical equations.Significant Figures Significant figures include numbers which can be read clearly from the scales ofthe measuring instrument plus a last uncertain number which is estimated between thesmallest scales of the instrument. It is important that measurements taken be expressedin the proper number of significant figures. The following are rules to be followed indetermining the number of significant figures: Rule 1. All nonzero digits are always significant. Examples: 72 465 five significant figures 7 246.5 five significant figures Rule 2. A zero between nonzero digits is always significant. Examples: 903 three significant figures 90.3 three significant figures Rule 3. A trailing zero after a decimal point is significant. Examples: 4 625.0 five significant figures 462.50 five significant figures 0.610 three significant figures 0.6100 four significant figures Rule 4. A zero used to fix a decimal point in a number less than 1 is not significant. Examples: 0.1256 four significant figures 0.01256 four significant figures Rule 5. A zero ending a number more than 1 may or may not be significant. Examples: 760 000 may have two to six significant figures The ambiguity of this last rule can be resolved by expressing these numbers inscientific notation. 7.6 × 105 two significant figures 7.600 × 10 5 four significant figures Energy in Society 11
  • 18. Scientific Notation and Measurement Very large and very small numbers can be conveniently expressed as powers of 10. Thenumber written to the right and above the figure 10 is called an exponent. The scientific notation is the system of expressing products with a number between 1 and 10 multipliedby an appropriate power of 10. A positive exponent tells how many times a number mustbe multiplied by 10 to obtain a certain number. For example, 1 × l03 means 1 should bemultiplied by 10 three times, i.e., 1 × 10 × 10 × 10 equals 1 000. Conversely, 1 × 10–5 meansto divide 1 by 10 five times. Therefore, 1 × 10–5 equals 0.00001. Note that 0.00001 shouldcontain the same number of significant figures as 1 × 10–5. The number to be multiplied by10 should always be between 1 and 10. Measurement is the process of comparing a specific quantity of matter with anagreed standard. It is a method of describing physical phenomena. There are two kindsof quantities of measurements: fundamental and derived. Fundamental quantities can bemeasured directly using specific instruments. Derived quantities are based on fundamentalmeasurement. They can be a combination of fundamental quantities or a combination offundamental and other derived quantities. In science, the system of measurement used is the International System of Units or theSI (Systeme Internationale d’ Unites). It was adopted for worldwide use in 1960.Precision and Accuracy In measurement, accuracy and precision are required. The terms precision and accuracyhave different meanings. The precision of a measurement is the degree of agreementbetween different values obtained under basically the same condition. It is a measure of thedegree to which measurements agree. A measurement is said to havea high degree of precision whenindependently obtained values closelyagree. That is, when several trials aredone under the same condition, thenumerical data that are obtained are Accurate but imprecise Inaccurate but precisevery close to one another. For example, three of yourclassmates were asked to measure thelength of a pencil. They obtained thefollowing results: 9.60 cm, 9.70 cm, and9.60 cm. You can say that the valuesobtained are precise because the valuesare close to one another. Inaccurate and imprecise Accurate and precise Fig. 1. Accuracy versus precision1 High School Science Today IV
  • 19. The accuracy of a numerical result is the degree of agreement between theexperimental result and the true value. It is quite possible in duplicate measurements tohave highly similar results while at the same time both could be far from the true value. Anerror of approximately the same measure may be involved in each. For example, the length of a pencil is 9.65 cm. This is the true value. Our experimentalresults are 9.60 cm, 9.70 cm, and 9.60 cm. If you get the average of these experimentalresults, which is 9.63 cm, you will see that the results are accurate because it is close to thetrue value. Many factors affect the precision and accuracy of experimental results. These factorsinclude condition of equipment, quality of material used, and environmental conditionssuch as temperature and pressure.Fundamental Quantities of Measurement Below are the seven fundamental quantities of measurement and the correspondingSI units.1. Length is the measure of distance from one point to another. The SI unit of length is meter (m). Meter was redefined in 1983 as the distance that light traveled in a vacuum 1 during a time interval of 299 792 458 of a second. Rulers, metersticks, tape measures, vernier calipers, and micrometer calipers are used to measure length.2. Mass is the measure of the quantity of matter in a body. The SI unit used to express mass is kilogram (kg). The standard kilogram is a block of platinum-iridium alloy, which is preserved at the International Bureau of Weights and Measures in France. A spring balance or scale can be used to measure mass.3. Time is the measure of duration or the interval between two events or phenomena. The SI unit of time is second (s). Instruments such as clocks and stopwatches are used to measure time.4. Temperature is the measure of the average kinetic energy of all molecules of a given substance. The SI unit of temperature is Kelvin (K). Thermometers are used to measure temperature.5. Luminous intensity is the measure of radiant intensity in a given direction. It also pertains to the brightness of light. Its SI unit is candela (cd). Radiometers and photometers are used to measure luminous intensity.6. Electric current is the measure of flow of electrical charges. The SI unit of electric current is ampere (A). An ammeter is used to measure electric current.7. Mole (mol) is the amount of substance which contains as many entities as there are atoms in 0.12 kilogram of carbon 12. Specifically, it is defined using Avogadro’s number, whose value is 6.02 × 1023 molecule/mol. Energy in Society 1
  • 20. Derived Quantities of Measurement1. Area is the amount of surface usually expressed in square meters (m2). Arectangle= lw Asquare= s2 Atriangle = 1 bh Acircle = r2 2 where A = area, l = length, w = width, s = side, b = base, h = height, and r = radius. The symbol π (pi) has a value of 3.1416 (estimated to four decimal places).2. Volume is the total space occupied by a body. Its SI unit is the cubic meter (m3). Vrectangular prism = lwh Vcylinder = πr2h where V = volume and r = radius3. Density is the ratio of mass to volume of a given material. Its SI unit is kilogram per cubic meter (kg/m3). =m V where = density, m = mass, and V = volume4. Speed is the distance traveled by an object per unit time. Its SI unit is meter per second (m/s). v= d t where v = speed, d = distance, and t = time5. Acceleration is the rate at which the velocity (a rate of change in position in a particular direction) of a moving body changes. The change in velocity may be in magnitude (speed), direction, or both. It is measured in meter per second squared (m/s2). a = ∆v ∆t where a = acceleration, ∆v = change in velocity, and ∆t = change in time6. Weight is the pull of gravity in an object. It is expressed in newtons (N). One newton is equal to 1 kg · m/s2. w = mg where w = weight, m = mass, and |g| = the magnitude of the acceleration due to gravity which is equal to 9.8 m/s2. SI provides prefixes which can be used with SI units. Table 1.1 lists the 20 approvedSI prefixes.1 High School Science Today IV
  • 21. Table 1.2 Prefixes for Powers of 10 Number Factor Name Symbol 1 000 000 000 000 000 000 000 000 1024 yotta Y 1 000 000 000 000 000 000 000 1021 zetta Z 1 000 000 000 000 000 000 1018 exa E 1 000 000 000 000 000 1015 peta P 1 000 000 000 000 1012 tera T 1 000 000 000 109 giga G 1 000 000 106 mega M 1 000 103 kilo k 100 102 hecto h 10 101 deca da 0.1 10–1 deci d 0.01 10–2 centi c 0.001 10–3 milli m 0.000 001 10–6 micro µ 0.000 000 001 10–9 nano n 0.000 000 000 001 10–12 pico p 0.000 000 000 000 001 10–15 femto f 0.000 000 000 000 000 001 10–18 atto a 0.000 000 000 000 000 000 001 10–21 zepto z 0.000 000 000 000 000 000 000 001 10–24 yocto y The SI units were developed to replace the English system of measurement becauseof the complexity in converting from one unit to another using the English system. Yards,ounces, inches, and quarts are units in the English system. Energy in Society 1
  • 22. Today, we still use a few units from the English system such as inches, miles, and feet.A conversion table was developed to facilitate conversion from the English system to themetric system and vice versa. Table 1.3 lists common conversion factors for the two systemsof measurement. Table 1.3 Conversion Factors of the English and Metric Systems of Measurement Length and Volume 1 in 2.54 cm 1 ft 0.3048 m 1m 39.37 in 1 mi 1.6093 km 1L 103 cm3 or 10–3 m3 Mass 1 kg 2.2 lbSample Problems:1. Annie is 5 ft 4 in tall. What is her height in meters? Solution: 12 in 5 ft × = 60 in 1 ft 5 ft 4 in = 5 ft + 4 in = 60 in + 4 in = 64 in 2.54 cm 1m 64 in × × = 1.6 m 1 in 100 cm2. What is the equivalent of the density of aluminum (2.7 g/cm3) in kilogram per cubic meter? ( 100 cm ) = 27 000 kg/ m3 3 2.7 g 1 kg × × cm3 1 000 g 1 m3 = 2.7 × 10 4 kg/ m3 Observe that in problem 2, the answer has the same number of significant figures asthat of the given. This should be done in converting one unit of measure to another.1 High School Science Today IV
  • 23. Exercises:1. Find the density of a book which measures 25 cm × 20 cm × 1.8 cm and has a mass of 0.5 kg.2. Elai is 180.02 cm tall. Express her height in meters. You now see the reason why having a good background in mathematics is important inphysics. Many physicists excel in mathematics like Isaac Newton. His book Principia wasa pioneering work in the field of mathematical physics. Some of Newton’s contributionsinclude the law of gravitational attraction, the discovery of the nature of white light, andthe development of differential and integral calculus. Using his discoveries, Newton was able to further work out the details of Earth’smotion, accurately estimate the mass of the sun and Earth, prove that tides were the resultof the moon’s gravitational attraction, explain the orbits of comets, and lay the foundationfor the treatment of wave motion. Accurate measurements are obtained when the instrument is properly calibrated and acorrect reading is made. Energy in Society 1
  • 24. Chapter ReviewI. Enriching Your Science Vocabulary Choose from the words inside the box the term that is being described in each phrase below. measurement biophysics accuracy speed acceleration astrophysics technology volume density weight precision scientific notation __________ 1. deals with the physical and chemical nature of celestial objects and events __________ 2. refers to the application of various methods and principles of physical science to the study of biological problems __________ 3. process of comparing a specific quantity of matter with an agreed standard __________ 4. rate at which the velocity of a moving body changes __________ 5. pull of gravity in an object __________ 6. distance traveled by an object per unit time __________ 7. ratio of mass to volume of a given material __________ 8. degree of agreement between several values obtained basically under the same conditions __________ 9. practical application of science __________ 10. extent to which a measured value agrees with the standard value of a quantityII. Assessing Your Knowledge A. Match the scientist with his or her achievement. Write the letter of your answer. _____ 1. Isaac Newton a. formulated the laws of motion and gravitation _____ 2. Albert Einstein b. explained the nature of light as an _____ 3. Galileo Galilei electromagnetic wave _____ 4. Heinrich Hertz c. postulated the theory of relativity _____ 5. James Clerk Maxwell d. combined electricity and magnetism into one coherent theory e. disproved the theory that heavy objects fall or accelerate faster than light objects B. Convert the following. 1. 10 mi to km 3. 86 km to m 2. 300 cm to ft 4. 45 in to cm1 High School Science Today IV

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