s Character

of pastors such as Jonathan Edwards are gone, and most people rationalize away God’s wrath by saying that if God is truly holy, then his mercy will overshadow his justness. R.C. Sproul suggests differently saying, â€Å"If God is holy at all, if God has an ounce of j... 's Character Free Essays on God\'s Character Ever since God’s relationship with man was twisted by the fall of Adam and Eve, people who believe in God have been trying to create an accurate understanding of what He is really like. Countless books and sermons have tried to portray his character, and there is perhaps no topic that is more widely disputed. God is eternal, omnipresent, wise, all-knowing, powerful, holy, good, sovereign, patient, and the list could go on and on. Although God is unchanging, people’s opinions of Him are constantly shifting, sometimes towards deeper understanding and sometimes towards ignorance. In modern times the thin spectrum of modern US culture that recognizes God emphasizes love but forgets holiness, the reformed circle stresses sovereignty but can downplay immanence, and in my personal life I often find myself paying more attention to God’s goodness and patience but not enough to his omniscience and wisdom. In modern North America, especially the United States, the general community has become wrapped up in political correctness and tolerance. It is becoming increasingly difficult to suggest that God would send someone to hell unless they have led a very sinful life. Most would rather avoid stepping on people’s toes by emphasizing God’s Love. Verses such as John 3:16 and 1 John 4:8 which say, â€Å"For God so loved the world†¦Ã¢â‚¬  and â€Å"†¦God is Love.† Are widely known even among non-Christians. It is very true that our God is a God of grace and forgiveness, but one must not forget that He is a holy God as well. God’s holiness and more specifically his justness are forgotten to a frightful degree in today’s day and age. The day in which people heeded the words of pastors such as Jonathan Edwards are gone, and most people rationalize away God’s wrath by saying that if God is truly holy, then his mercy will overshadow his justness. R.C. Sproul suggests differently saying, â€Å"If God is holy at all, if God has an ounce of j...

Whats a Good PSAT Score for a Sophomore

What's a Good PSAT Score for a Sophomore SAT / ACT Prep Online Guides and Tips You wouldn't go for your driver's license test before ever getting behind the wheel, right? In reality, you'd practice your three-point turns and parallel parking first so you're ready and know what to expect when the real test comes. Just as you suspected, this scenario's an analogy for the PSAT. Rather than sitting for it junior year without a practice run, you can improve your performance if you've already taken it in 10th grade. Taking the PSAT as a sophomore is a great, low-pressure way to familiarize yourself with the test,gauge your level, and figure out where you need to improve. With this in mind, we'll look at what PSAT scores aregood for sophomores and how to improve them even more for junior year. But first, let's consider howthe PSAT is scored. How Is the PSAT Scored? The new PSAT is scored between 320 and 1520 points. You'll get two scaled scores between 160 and 760: one for Math and one for Reading and Writing combined (called Evidence-Based Reading and Writing, or EBRW). You'll also get to see how you performed on each of the three sections with a test score between 8 and 38. (This scoring scale differs from that on the old PSAT, which gave you 20-80 points on three separate sections.) The new PSAT scoring scale helps you predict your SAT scores. If you score 1500 on the PSAT, you're likely to achieve a similarly high score on the SAT. The scale is shifted about 80 points lower than that of the SAT (which has a total score range of 400-1600) sincethe PSAT is a slightly easier test. Therefore, you can only compare the scores up to about 1520; beyond that, you can't equate a perfect PSAT score with a perfect SAT score. Your PSAT score report will give you lots of data, including your scaled scores, section scores, and subscores, which further break down your performance. For the sake of figuring out what makes a good PSAT score for a sophomore, let's consider another important piece of data: your percentiles. Percentiles compare your section and composite scores with those of other test takers. So if your Math score falls in the 80th percentile, you've scored higher than 80% of test takers (and the remaining 20% scored higher than you). Basically, the higher your percentile, the better you scored on the PSAT compared with everyone else. Read on to learn about percentiles and how they can help us answer our question of what's a good PSAT score for a 10th grader. Want to improve your SAT score by 160points or your ACT score by 4 points?We've written a guide for each test about the top 5 strategies you must be using to have a shot at improving your score. Download it for free now: What's a Good PSAT Score for a Sophomore? We can define a"good" PSAT score for a sophomore as one that's higher than the 75th percentile.This means that you scored higher than 75% of other sophomores who took the PSAT.For sophomores, 75th percentile scores are around 520-540on each section, or about 1050-1060 total. An "OK" PSAT score for a sophomore is one that's higher than the 50th percentile, meaning you scored higher than half of test takers. In contrast, anexcellent score is one that's higher than the 90th percentile, or 90% of test takers. This chart shows the minimum section and composite scores you'd need to hit the 50th, 75th, 90th, and 99th percentiles on the PSAT: PSAT Percentile (10th Grade) EBRW Score Math Score Composite Score 50% (OK) 460-470 450-460 910-920 75% (Good) 540 520-530 1050-1060 90% (Excellent) 600-610 580-590 1180 99% (Top) 700 710 1370 Source: Understanding PSAT/NMSQT Scores 2018 Based on that reasoning, a good PSAT score for a sophomore is a composite score higher than 1050-1060, an OK score is one higher than a 920, and an excellent score is anything higher than a 1180. What DoPSAT Score Percentiles Mean? To understand how we chose the scores to represent "good," "OK," and "excellent" PSAT scores, as well as how you can interpret PSAT scores,you'll need to understandPSAT percentiles. This section will give you a more in-depth look at PSAT percentiles and the information you can get from them. YourPSAT score report will feature lots of score types and data. Among this data, you'll get not just one but two percentiles comparing your scores with those of other students. These percentiles are called the Nationally Representative Percentile and the User Percentile. The reason behind using two percentiles remains vague, and some educators have suggested that the College Board uses the Nationally Representative Percentile as a way to inflate students' scores and make the PSAT appear less competitive than it really is. Regardless, we'll focus on User Percentiles, which compare all students in a grade who typically take the PSAT (as opposed to the other percentile, which includes all students in a grade, even those who didn't take the PSAT- weird, I know). Below is a chart based on info from the College Board's 2018 PSAT score report, which gives PSAT User Percentiles specifically for 10th graders. As you look through the data, note that the same scores translate to slightly different percentiles. In past years, Math tended to be more competitive than Evidence-Based Reading and Writing (EBRW). Here, the comparisons are less straightforward. Check out the data, and then read on for further interpretation of how these sections compare. PSAT Score EBRW Percentile (10th Grade) Math Percentile (10th Grade) 760 99+ 99+ 750 99+ 99+ 740 99+ 99 730 99+ 99 720 99+ 99 710 99 99 700 99 98 690 98 98 680 98 98 670 97 97 660 97 97 650 96 97 640 95 96 630 94 95 620 92 95 610 91 94 600 89 92 590 87 91 580 85 89 570 83 87 560 80 85 550 78 82 540 75 80 530 72 77 520 68 74 510 65 71 500 62 68 490 59 64 480 55 60 470 52 56 460 49 52 450 45 48 440 42 43 430 39 39 420 35 35 410 32 30 400 28 26 390 25 21 380 21 17 370 17 14 360 14 11 350 11 8 340 8 6 330 6 5 320 4 4 310 3 3 300 2 2 290 1 and below 2 and below In past years, Math was pretty much always more competitive than Reading and Writing; however, Reading and Writing has recently become more competitive. This means that most of the time you'll need to achieve a slightly higher score on EBRW to make it into the same percentile as you did on Math. For example, a Math score of 500 puts you in the 68th percentile, but the same score on EBRW puts you in only the 62nd percentile. Why Are PSAT Scores Important for Sophomores? Your sophomore year PSAT scores aren’t as important as your PSAT scores from your junior year when you’ll be able to compete for National Merit, but they're still useful. You can use your sophomore PSAT scores to estimate how well you’ll do on the PSAT next year and on the SAT later on. This can help you gauge how much studying you'll need to do to qualify for National Merit and/or meet your SAT score goals. Preparing for National Merit as a Sophomore The National Merit Scholarship Corporation (NMSC) identifies juniors who get top scores on the PSAT. Students whose PSAT scores are in the top 1% are named Semifinalists. Reaching this stage can give you a big boost in college admissions and make you eligible for numerous scholarships,. Thus, many students who take the PSAT as sophomores do so to prepare themselves for when they take the PSAT as juniors and can compete for National Merit. There are several things you can do as a sophomore to help you prepare for the PSAT as a junior and potentially qualify you for National Merit. If you're already scoring in the 95th percentile or above as a sophomore, you're well on track to qualifying as a Semifinalist and eventually Finalist. While these are outstanding scores, National Merit scholarships only go to the top 1% of juniors, so you'll have to do some serious prep to compete with other juniors and bring up your scores to the top of the pack by the following year. If National Merit is in your sights, you'll want to aim for a score of around 1440 on the PSAT, or about 35-36 as your "test score" on each section (when you take the test as a junior). The exact score you need to qualify varies by state. Check out the cutoff scores here, as well as all the other criteria you must meet to be competitive for National Merit. Remember, though, that you have lots of time to prepare for both the PSAT and SAT, so if you’re not happy with your scores, there’s still time to develop a solid study plan and improve your scores. Speaking of prep... Disappointed with your PSAT performance? Want to improve your PSAT score by 150 points? We have the industry's leading PSAT prep program. Built by Harvard grads and SAT full scorers, the program learns your strengths and weaknesses through advanced statistics, then customizes your prep program to you so that you get the most effective prep possible. Check out our 5-day free trial today: What Can You Do to Prepare for the PSAT? 3 Key Tips There are multiple steps you can take to prepare for both the PSAT you take sophomore year and the one you take junior year. Even a small amount of preparation can translate into significant score increases, so be sure to take a look at these tips and make use of them before test day! #1: Set Target PSAT Scores Before you take the PSAT your sophomore year, consider setting a target score to give you a goal to aim for while studying and to make sure you're on track to meet your goals for your junior-year PSAT and eventually SAT. A potential goal could be scoring in at least the 70th percentile, for example. Or you might aim higher, such as the 95th percentile, if you're hoping to qualify for National Merit as a junior. Once you get the results for your sophomore-year PSAT, you can start to set goals for your junior-year PSAT. Again, if you're aiming for National Merit, you'll need to get a composite score of about 1440 to qualify. With serious prep, you could raise your PSAT score by hundreds of points. Even apart from all your studying, you're likely to improve regardless since you'll be a year older with an additional year of high school under your belt! #2: Take PSAT Practice Tests The best way to improve your PSAT scores is to start practicing! You can use official PSAT practice tests as well as official SAT questions available through the College Board website and Khan Academy (a partner website). The abundance of practice material for the old (pre-2015) PSAT doesn't have to go to waste either. Many of these questions, especially the Math and reading comprehension ones, are still relevant. Just make sure to familiarize yourself with the changes to the test so you can shift your focus to the most important skills. If you're disappointed with your sophomore-year PSAT scores, don't worry! You still have plenty of time to learn and practice. Use your feelings as motivation to improve next year through focused, disciplined, and effective test prep. #3: Target Your Weaknesses After you've taken your first PSAT practice test, look it over and see which questions you got wrong and which ones you got right. Did you score well on Reading and Writing but struggle with Math? Were there specific types of questions or topics that gave you trouble? Take time to figure out where you need to make the most improvements. Then, get to work targeting those weaknesses! For each question you got wrong on your practice test, look at the correct answer and try to re-solve it, using the correct answer as a guide. If you still can't figure it out, read that question's answer explanation to understand what you did wrong and how to solve it. When studying, be sure to focus extra attention on your weak areas. Brush up on the topics themselves if you need to, and answer lots of practice problems until you feel more confident. Do all of this, and you'll be well on your way to a great PSAT score! What's Next? The PSAT is great prep for the SAT, but you might also be taking the SAT or ACT as practice. Learn about good SAT and ACT scores for sophomores so you can get a better idea of what scores to aim for on test day. Do your PSAT scores predict your SAT scores? Our guide offers a detailed look at the connection between the two tests and your scores on them. Got questions about the PSAT format? Read this complete guide to the redesigned PSAT. Want to improve your SAT score by 160 points or your ACT score by 4 points?We've written a guide for each test about the top 5 strategies you must be using to have a shot at improving your score. Download it for free now:

Female Characters in Flannery O'Conner Short Stories Essay

Female Characters in Flannery O'Conner Short Stories - Essay Example Some have an aspect of madness, some are very assertive and others are very devout Christians. The three short stories that will be critiqued for the elements of women are , â€Å"Everything That Rises Must Converge,† â€Å"The Life You Save May Be Your Own,† and â€Å"A Circle In the Fire.† All three stories provide the reader with a look into the traditional, Southern woman and her need for survival. 2 â€Å"Everything that Rises Must Converge† In the beginning of this story, the reader is introduced to Julian and his mother. They are on their way to a â€Å"reducing class at the Y† (O’Connor 1) where his mother must lose 20 pounds. The reader is immediately pulled into the story because the writing is very clear and crisp. O’Connor has the reader standing behind the mother and watching her try on her hat to get it to fit her head in just the right way. The author writes, â€Å"she lifted the hat one more time and set it down slowly on top of her head† (â€Å"Everything† 1). This automatically sets the mood for what is going to happen and the reader understands that the mother is elderly by the â€Å"grey hair protrude on either side of her florid face †¦Ã¢â‚¬  (â€Å"Everything† 1). ... This mother and son conflict continues throughout the story. His mother was â€Å"still [living] according to the laws of her own fantasy world† (â€Å"Everything† 6) where she would always remain. He saw the world differently and was attempting to make her see the world for what it was—a place that had changed. His mother still thought she was living in a time when slaves were slaves and everything in her mind was right. This is not the world they were living in now. Bryan N. Wyatt states that Julian wrestles with what to do with his mother since he has become emotionally detached from her. He thinks about abandoning her at a bus stop to get out of her clutches. Michael W. Crocker and Robert C. Evans note that the convergence in the story has to do with Julian’s mother being seen as n outsider of the society in which she lives and having to come to terms with the fact that life is not what it used to be – that blacks are now free and they can move around as whites and they can work in jobs instead of on plantations (par. 7). This is a sad stroke of luck for Julian’s mother because it is difficult for her to deal with this truth. In fact, this is so difficult that she walks down the street, has a heart attack and dies at the end of the story when she is confronted with reality. To say that this is a poignant ending is an understatement. The reader can identify with Julian’s mother and with Julian because these two people are seen in everyone’s family. The mother in this short story is very traditional, and she may be suffering from delusions as she lives in her fantasy world. She only understands good Southern hospitality that she grew up with and she is not prepared for the life outside of this

Study of Anti-Dumping by a Regional Trade Agreement Dissertation

Study of Anti-Dumping by a Regional Trade Agreement - Dissertation Example Anti-dumping policies are typically rationalized on the basis that they are necessary for eliminating harmful dumping practices by exporters and to promote fair competition in trade (Davis, 2009). Even so, research demonstrates that despite the fact that the WTO’s anti-dumping policies are intended to protect the interests of domestic producers and to promote fair competition and trade, the frequent use of the WTO’s Anti-dumping Agreement by some regional actors such as the EU, the USA and China demonstrates that the WTO’s Anti-Dumping Agreement is exploited for unnecessary protectionisms and retaliatory measures. Moreover, Article XXIV of the General Agreement on Tariffs and Trade 1994 allows the creation of Regional Trade Agreements (RTAs) and thus together with the Anti-Dumping Agreement exacerbates the WTO’s liberalized multilateral world trade system and particularly its goal of indiscriminate trade. This research study examines the use of the WTOâ₠¬â„¢s Anti-Dumping policies in RTAs and demonstrates exploitation via unnecessary protectionism and retaliatory measures. It is concluded that the trends in regional trade agreement anti-dumping policies and practices fully demonstrate that WTO members are free to exploit the Anti-Dumping Agreement contained in Article VI of the General Agreement on Tariffs and Trade 1994 (GATT) for excessive protectionism, retaliatory measures and for discriminatory trade practices contrary to GATT’s non-discrimination trade policies.... Table of Contents Abstract 3 Table of Contents 3 Chapter One 5 Introduction to the Study 5 I.Background to the Study 5 II.Research Questions 9 III.Aims and Objectives of the Study 10 V.Significance of the Study 11 VI.Research Methods 11 VII.Organization of the Study 12 Chapter Two 12 A Review of the Literature 12 I.Introduction 13 II.RTAs 13 A.Definition 13 B.Typologies of RTAs 14 D.Conclusion 23 III.Conceptualizing Anti-Dumping 24 A.Definitions 24 B.The Advantages and Disadvantages of Anti-Dumping Policies and Measures 26 C.Conclusion 30 IV.The WTO’s International Trade System 31 V.Conclusion 33 Chapter Three 34 Regional Trade Agreements Within the World Organization’s Multilateral System 34 I.Introduction 34 II.Snapshot of the WTO’s Legal Regime Facilitating RTAs in the WTO’s Multilateral Trade System 35 III.The WTO’s Legal Framework for the Formation of RTAS 36 A.Customs Unions 45 B.Free Trade Arrangements 47 VI.Conclusion 49 Chapter Four 49 The WTO’s Anti-Dumping Legal Framework 49 I.Introduction 49 II.Anti-Dumping Under the WTO 50 III.Conclusion 56 Chapter Five 57 Findings/Conclusion 57 Chapter One Introduction to the Study I. Background to the Study Dumping occurs when products or goods are sold on the global market or exported to a domestic market at a relative low price compared to like products or goods (Raju, 2008). According to the World Trade Organization’s (WTO) General Agreement on Tariffs and Trade(GATT) 1994, dumping refers to the sale of goods and products at a price lower that its ordinary value (General Agreement on Tariffs and Trade 1994, Article VI). According to GATT (1994: Article VI) the ordinary value of goods and products is the price at which those goods and products are

Natural child birth VS. Medicated child birth Essay Example for Free

Natural child birth VS. Medicated child birth Essay Abstract: Natural childbirth and medicated birth are the two options practiced all around the world by the gynecologists, these days. However there are some issues related to both the birth process. In this paper we will discuss the pros and cons of both the natural child birth and the medicated child birth. Introduction Natural childbirth: it is a natural process with minimum medical intervention, specifically the use of pain relives medications and surgical interventions (Vernon, D (2005) Medicated child birth: in this type of birth, doctor make use of pain killers and other instruments like episiotomies, forceps and ventouse deliveries and caesarean sections during the delivery process. Every woman during her delivery undergoes pain which is a normal physiological reaction. In a normal birth, pain makes the women to react against the pain by tensing and fighting it. Majority of women around the world prefers natural child births however in some cases the mother prefers to be medicated thus reliving pain. Birth pain is sudden and intense. However, with every contraction the pain gradually fades away resulting in birth of a child. (Sakala, C. , M. Corry, and H. Goer. (2004) So for a mother there are both the options available either to select natural birth or a medicated child birth. Natural child birth is a natural process and there is now side effect except the mother undergoes sever pain. However in case of medicated child birth is artificial process therefore it does have some side effects despite it’s practiced very frequently all around the world Here are some of the pros and cons of both natural and the medicated child birth: Benefits of Natural Childbirth Natural child birth is completely without any medication. Remember that medicine is a medicine and, and even the most secure medicines also have some side effects Mothers that go through natural child birth is able to move freely throughout labor and after as the new researches reveals that medicated birth makes it difficult to move during and after the birth. ( Anderson, G. , et al. (2000) In natural childbirth women feel their bodys reflex, there how they can respond better by pushing faster, as the medication does affect the reflexes thus prolonging the pushing time. (World Health Organization Department of Reproductive Health and Research. (1999) Unmediated birth is natural process and the pain during the birth is also natural that guides the mother to seek specific positions that might help the child to move easily to get into right position of delivery. In majority of cases Mothers has fast recovery after a natural childbirth since they can move freely and easily. Generally they eat immediately and their appetite is normal. In natural child birth Endorphins is secreted within placenta and umbilical cord of the mother. That secretion helps the baby to deliver easily and get adjusted to new environment comfortably. (Lieberman, E. and C. ODonoghue (2002) Naturally delivered babies are better responsive and show more interest in pre-breastfeeding behaviors such as sucking and massaging the mothers breasts, as well as the proper length of time they spend nursing during the first one and a half hour. Natural birth also increases the possibility of a healthier and fast recovery because of better hormonal balance. (Righard, L. and M. Alade. (1990). This is because a woman who has given birth with minimal intercession does not need to recover from major abdominal surgery, instrumental delivery, and cut of the perineum, any damage from IV lines, or severe stomach pain, headache backache caused by the use of medication. Natural childbirth increases the natural delivery physiology and laboring progress of healthy, well- feed women and increases interventions in the normal course of natural childbirth. Benefits of Medicated Birth Medicated Birth has a lot of benefits and is been adapted by the mothers all over the world. Some of the benefits are as follows: Women that experience a very long labor pain can benefit from using pain medication to get some relief prior to pushing stage. (Simkin, P. (1992) if the woman is finding the pain unbearable, it will definitely affect the delivery process, pain medication would definitely act as an aiding factor so that her body might not fight against the labor. (E. Jones, Pregnancy, Contraception, and Family Planning Services in Industrialized Countries (1989) similarly if the woman is experiencing some sort of fear, medication would help her by reliving her from severe pain and anxiety. However on the other hand it does have side effects depending upon person to person. Sometimes it is found that Medication has caused the baby sleepy as the anesthesia can penetrate through the placenta. (Ransjo-Arvidson A. B. , Matthiesen. (2001) Moreover pain guides the mother to adjust her position through which the child can adjust within if the child is posterior. However in case of medication the mother can not feel the pain to adjust herself thus may case certain complications in some cases. (Uvnas-Moberg, K. (1998) Conclusion Mothers have the ability to give birth naturally. Despite the women faces the pain but the pain goes away gradually. It is a fast process and has no side effects. The baby is normal and responsive. Pain medication is a great resource in very difficult and prolonged labors when the mother loses her patience to deliver the baby. In such cases epidural is very much effective. Anaesthetics may increase the likelihood of complications ( Knapp, L. (1996) We can find variety of pain killers out there in the market. If the right medicine is used I can help the delivery. Most pain killers do not take pain completely away. It makes pain bearable for the mother thus can concentrate on the birth. However in medicated birth mother always need continuous assistance all through the process.

Extraversion :: essays research papers

Cross Cultural Evidence for the Fundamental Features of Extraversion   Ã‚  Ã‚  Ã‚  Ã‚  There has yet to be any determining evidence defines the characteristics of extraversion. The experimenters in this particular experiment have hypothesized that the facets of extraversion are somehow linked by reward sensitivity. This hypothesis was also tested against a model in which they are linked by sociability. There has been much work on this topic in the past, beginning with the works of Jung and James in the early 20th century—to the work of Watson and Clark in 1997. And even after a century of study, they are still unable to truly define the characteristics of the extraversion dimension of personality. In the many attempts to define extraversion, Watson and Clark have defined six basic facets of the personality trait. These are: venturesome, affiliation, positive affectivity, energy, ascendance, and ambition. Researchers Depue and Collins, in 1999, also offered a more succinct depiction of the characteristics of extraversion, this only having thre e basic parts. The first being affiliation, the enjoyment and value of close interpersonal bonds, also being warm and affectionate. The second, agency, being socially dominant, enjoying leadership roles, being assertive and exhibitionistic, and having a sense of potency in accomplishing goals. The final facet being impuslivity, but this one has been argued upon whether it should be included at all in the characteristics of extraversion at all.   Ã‚  Ã‚  Ã‚  Ã‚  Their first study was composed of 443 college students from two large universities in the Midwest. The participants were offered credit in their introductory psychology classes in return for their participation. They completed a questionnaire as part of their participation. 52% of the participants were men, and 48% were women. 94% were between the ages of 18 and 25. Only the 404 students that had complete data were used to set up the model that the experimenters formed. The second study tried to show any coincidence between the findings of American students and international ones.

Ncert Physics Book

Presents NCERT Text Books NCERT Text Books: 11th Class Physics About Us: Prep4Civils, website is a part of Sukratu Innovations, a start up by IITians. The main theme of the company is to develop new web services which will help people. P rep4Civils is an online social networking platform intended for the welfare of people who are preparing for Civil services examinations. The whole website was built on open-source platform WordPress. Contact Details: Website: http://www. prep4civils. com/ Email: [email  protected] comDisclaimer and Terms of Use: By following Creative Common License, for the welfare of large student body we are merging all the PDF files provided by NCERT website and redistributing the files by giving proper credit to NCERT website and the redistribution is based on the norms of Creative Common License. We are not commercially distributing the files. People who are downloading these files should not be engaged in any sort of sales or commercial distribution of these files. They can redistribute these copies freely by giving proper credit to the original author, NCERT (http://www. ncert. nic. in/NCERTS/textbook/textbook. tm) and â€Å"Prep4Civils† (http://www. prep4civils. com/) by providing proper hyperlinks of the websites. Any sort of cliches can be addressed at [email  protected] com and proper action will be taken. CONTENTS FOREWORD PREFACE A NOTE FOR THE TEACHER CHAPTER iii v x 1 PHYSICAL WORLD 1. 1 1. 2 1. 3 1. 4 1. 5 What is physics ? Scope and excitement of physics Physics, technology and society Fundamental forces in nature Nature of physical laws CHAPTER 1 2 5 6 10 2 UNITS AND MEASUREMENTS 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 2. 10 Introduction The international system of units Measurement of length Measurement of massMeasurement of time Accuracy, precision of instruments and errors in measurement Significant figures Dimensions of physical quantities Dimensional formulae and dimensional equations Dimensional analysis and its applications CHAPTER 16 16 18 21 22 22 27 31 31 32 3 MOTION IN A STRAIGHT LINE 3. 1 3. 2 3. 3 3. 4 3. 5 3. 6 3. 7 Introduction Position, path length and displacement Average velocity and average speed Instantaneous velocity and speed Acceleration Kinematic equations for uniformly accelerated motion Relative velocity CHAPTER 39 39 42 43 45 47 51 4 MOTION IN A PLANE 4. 1 4. 2 4. 3 4. 4 4. 5 IntroductionScalars and vectors Multiplication of vectors by real numbers Addition and subtraction of vectors – graphical method Resolution of vectors 65 65 67 67 69 CK xii 4. 6 4. 7 4. 8 4. 9 4. 10 4. 11 Vector addition – analytical method Motion in a plane Motion in a plane with constant acceleration Relative velocity in two dimensions Projectile motion Uniform circular motion CHAPTER 71 72 75 76 77 79 5 LAWS OF MOTION 5. 1 5. 2 5. 3 5. 4 5. 5 5. 6 5. 7 5. 8 5. 9 5. 10 5. 11 Introduction Aristotle’s fallacy The law of inertia Newton’s first law of motion Newton ’s second law of motion Newton’s third law of motion Conservation of momentumEquilibrium of a particle Common forces in mechanics Circular motion Solving problems in mechanics CHAPTER 89 90 90 91 93 96 98 99 100 104 105 6 WORK, ENERGY AND POWER 6. 1 6. 2 6. 3 6. 4 6. 5 6. 6 6. 7 6. 8 6. 9 6. 10 6. 11 6. 12 Introduction Notions of work and kinetic energy : The work-energy theorem Work Kinetic energy Work done by a variable force The work-energy theorem for a variable force The concept of potential energy The conservation of mechanical energy The potential energy of a spring Various forms of energy : the law of conservation of energy Power Collisions CHAPTER 114 116 116 117 118 119 120 121 123 126 28 129 7 SYSTEM OF PARTICLES AND ROTATIONAL MOTION 7. 1 7. 2 7. 3 7. 4 7. 5 7. 6 7. 7 7. 8 7. 9 7. 10 Introduction Centre of mass Motion of centre of mass Linear momentum of a system of particles Vector product of two vectors Angular velocity and its relation with linear veloci ty Torque and angular momentum Equilibrium of a rigid body Moment of inertia Theorems of perpendicular and parallel axes 141 144 148 149 150 152 154 158 163 164 CK xiii 7. 11 7. 12 7. 13 7. 14 Kinematics of rotational motion about a fixed axis Dynamics of rotational motion about a fixed axis Angular momentum in case of rotations about a fixed axisRolling motion CHAPTER 167 169 171 173 8 GRAVITATION 8. 1 8. 2 8. 3 8. 4 8. 5 8. 6 8. 7 8. 8 8. 9 8. 10 8. 11 8. 12 Introduction Kepler’s laws Universal law of gravitation The gravitational constant Acceleration due to gravity of the earth Acceleration due to gravity below and above the surface of earth Gravitational potential energy Escape speed Earth satellite Energy of an orbiting satellite Geostationary and polar satellites Weightlessness 183 184 185 189 189 190 191 193 194 195 196 197 APPENDICES 203 ANSWERS 219 CK CK CONTENTS FOREWORD PREFACE A NOTE FOR THE TEACHERS CHAPTER iii vii x 9 MECHANICAL PROPERTIES OF SOLIDS 9. 9. 2 9. 3 9. 4 9. 5 9. 6 9. 7 Introduction Elastic behaviour of solids Stress and strain Hooke’s law Stress-strain curve Elastic moduli Applications of elastic behaviour of materials CHAPTER 231 232 232 234 234 235 240 10 MECHANICAL PROPERTIES OF FLUIDS 10. 1 10. 2 10. 3 10. 4 10. 5 10. 6 10. 7 Introduction Pressure Streamline flow Bernoulli’s principle Viscosity Reynolds number Surface tension CHAPTER 246 246 253 254 258 260 261 11 THERMAL PROPERTIES OF MATTER 11. 1 11. 2 11. 3 11. 4 11. 5 11. 6 11. 7 11. 8 11. 9 11. 10 Introduction Temperature and heat Measurement of temperature Ideal-gas equation and absolute temperatureThermal expansion Specific heat capacity Calorimetry Change of state Heat transfer Newton’s law of cooling CHAPTER 274 274 275 275 276 280 281 282 286 290 12 THERMODYNAMICS 12. 1 12. 2 Introduction Thermal equilibrium 298 299 CK CK xii 12. 3 12. 4 12. 5 12. 6 12. 7 12. 8 12. 9 12. 10 12. 11 12. 12 12. 13 Zeroth law of thermodynamics Heat, internal ene rgy and work First law of thermodynamics Specific heat capacity Thermodynamic state variables and equation of state Thermodynamic processes Heat engines Refrigerators and heat pumps Second law of thermodynamics Reversible and irreversible processes Carnot engine CHAPTER 300 300 302 03 304 305 308 308 309 310 311 13 KINETIC THEORY 13. 1 13. 2 13. 3 13. 4 13. 5 13. 6 13. 7 Introduction Molecular nature of matter Behaviour of gases Kinetic theory of an ideal gas Law of equipartition of energy Specific heat capacity Mean free path CHAPTER 318 318 320 323 327 328 330 14 OSCILLATIONS 14. 1 14. 2 14. 3 14. 4 14. 5 14. 6 14. 7 14. 8 14. 9 14. 10 Introduction Periodic and oscilatory motions Simple harmonic motion Simple harmonic motion and uniform circular motion Velocity and acceleration in simple harmonic motion Force law for simple harmonic motion Energy in simple harmonic motion Some systems executing SHMDamped simple harmonic motion Forced oscillations and resonance CHAPTER 336 337 339 341 343 345 346 347 351 353 15 WAVES 15. 1 15. 2 15. 3 15. 4 15. 5 15. 6 Introduction Transverse and longitudinal waves Displacement relation in a progressive wave The speed of a travelling wave The principle of superposition of waves Reflection of waves 363 365 367 369 373 374 CK CK xiii 15. 7 15. 8 Beats Doppler effect 379 381 ANSWERS 391 BIBLIOGRAPHY 401 INDEX 403 CK CHAPTER ONE PHYSICAL WORLD 1. 1 WHAT IS PHYSICS ? 1. 1 What is physics ? 1. 2 Scope and excitement of physics 1. 3 Physics, technology and society 1. 4 Fundamental forces in nature 1. Nature of physical laws Summary Exercises Humans have always been curious about the world around them. The night sky with its bright celestial objects has fascinated humans since time immemorial. The regular repetitions of the day and night, the annual cycle of seasons, the eclipses, the tides, the volcanoes, the rainbow have always been a source of wonder. The world has an astonishing variety of materials and a bewildering diversity of life and behaviour. The inquiring and imaginative human mind has responded to the wonder and awe of nature in different ways. One kind of response from the earliest times has been to observe the hysical environment carefully, look for any meaningful patterns and relations in natural phenomena, and build and use new tools to interact with nature. This human endeavour led, in course of time, to modern science and technology. The word Science originates from the Latin verb Scientia meaning ‘to know’. The Sanskrit word Vijnan and the Arabic word Ilm c onvey similar meaning, namely ‘knowledge’. Science, in a broad sense, is as old as human species. The early civilisations of Egypt, India, China, Greece, Mesopotamia and many others made vital contributions to its progress. From the sixteenth century onwards, great strides were made n science in Europe. By the middle of the twentieth century, science had become a truly international enterprise, with many cultures and countries contributing to its rapid growth. What is Science and what is the so-called Scientific Method ? Science is a systematic attempt to understand natural phenomena in as much detail and depth as possible, and use the knowledge so gained to predict, modify and control phenomena. Science is exploring, experimenting and predicting from what we see around us. The curiosity to learn about the world, unravelling the secrets of nature is the first step towards the discovery of science.The scientific method involves several interconnected steps : Systematic observations, controlled experiments, qualitative and 2 quantitative reasoning, mathematical modelling, prediction and verification or falsification of theories. Speculation and conjecture also have a place in science; but ultimately, a scientific theory, to be acceptable, must be verified by relevant observations or experiments. There is much philosophical debate about the nature and method of science that we need not discuss here. The interplay of theory and observation (or experiment) is basic to the progress of science. Science is ever dynamic.There is no ‘final’ theory in science and no unquestioned authority among scientists. As observations improve in detail and precision or experiments yield new results, theories must account for them, if necessary, by introducing modifications. Sometimes the modifications may not be drastic and may lie within the framework of existing theory. For example, when Johannes Kepler (1571-1630) examined the extensive data on planetary motion collected by Tycho Brahe (1546-1601), the planetary circular orbits in heliocentric theory (sun at the centre of the solar system) imagined by Nicolas Copernicus (1473–1543) had to be replaced by elliptical rbits to fit the data better. Occasionally, however, the existing theory is simply unable to explain new observations. This causes a major upheaval in science. In the beginning of the twentieth century, it wa s realised that Newtonian mechanics, till then a very successful theory, could not explain some of the most basic features of atomic phenomena. Similarly, the then accepted wave picture of light failed to explain the photoelectric effect properly. This led to the development of a radically new theory (Quantum Mechanics) to deal with atomic and molecular phenomena. Just as a new experiment may suggest an lternative theoretical model, a theoretical advance may suggest what to look for in some experiments. The result of experiment of scattering of alpha particles by gold foil, in 1911 by Ernest Rutherford (1871–1937) established the nuclear model of the atom, which then became the basis of the quantum theory of hydrogen atom given in 1913 by Niels Bohr (1885–1962). On the other hand, the concept of antiparticle was first introduced theoretically by Paul Dirac (1902–1984) in 1930 and confirmed two years later by the experimental discovery of positron (antielectron) by Carl Anderson. P HYSICS Physics is a basic discipline in the category f Natural Sciences, which also includes other disciplines like Chemistry and Biology. The word Physics comes from a Greek word meaning nature. Its Sanskrit equivalent is Bhautiki that is used to refer to the study of the physical world. A precise definition of this discipline is neither possible nor necessary. We can broadly describe physics as a study of the basic laws of nature and their manifestation in different natural phenomena. The scope of physics is described briefly in the next section. Here we remark on two principal thrusts in physics : unification and reduction. In Physics, we attempt to explain diverse hysical phenomena in terms of a few concepts and laws. The effort is to see the physical world as manifestation of some universal laws in different domains and conditions. For example, the same law of gravitation (given by Newton) describes the fall of an apple to the ground, the motion of the moon around the earth and the motion of planets around the sun. Similarly, the basic laws of electromagnetism (Maxwell’s equations) govern all electric and magnetic phenomena. The attempts to unify fundamental forces of nature (section 1. 4) reflect this same quest for unification. A related effort is to derive the properties of a igger, more complex, system from the properties and interactions of its constituent simpler parts. This approach is called reductionism and is at the heart of physics. For example, the subject of thermodynamics, developed in the nineteenth century, deals with bulk systems in terms of macroscopic quantities such as temperature, internal energy, entropy, etc. Subsequently, the subjects of kinetic theory and statistical mechanics interpreted these quantities in terms of the properties of the molecular constituents of the bulk system. In particular, the temperature was seen to be related to the average kinetic energy of molecules of the system. . 2 SCOPE AND EXCITEMENT OF PHYSICS We can get some idea of the scope of physics by looking at its various sub-disciplines. Basically, there are two domains of interest : macroscopic and microscopic. The macroscopic domain includes phenomena at the laboratory, terrestrial and astronomical scales. The microscopic domain includes atomic, molecular and nuclear P HYSICAL WORLD phenomena*. Classical Physics deals mainly with macroscopic phenomena and includes subjects like Mechanics, Electrodynamics, Optics a nd T hermodynamics . Mechanics founded on Newton’s laws of motion and the law of gravitation is concerned with the motion (or quilibrium) of particles, rigid and deformable bodies, and general systems of particles. The propulsion of a rocket by a jet of ejecting gases, propagation of water waves or sound waves in air, the equilibrium of a bent rod under a load, etc. , are problems of mechanics. Electrodynamics deals with electric and magnetic phenomena associated with charged and magnetic bodies. Its basic laws were given by Coulomb, Oersted, Fig. 1. 1 chemical process, etc. , are problems of interest in thermodynamics. The microscopic domain of physics deals with the constitution and structure of matter at the minute scales of atoms and nuclei (and even ower scales of length) and their interaction with different probes such as electrons, photons and other elementary particles. Classical physics is inadequate to handle this domain and Quantum Theory is currently accepted as the proper framework for explaining microscopic phenomena. Overall, the edifice of physics is beautiful and imposing and you will appreciate it more as you pursue the subject. Theory and experiment go hand in hand in physics and help each other’s progress. The alpha scattering experiments of Rutherford gave the nuclear model of the atom. Ampere and Faraday, and encapsulated by Maxwell in his famous set of equations.The motion of a current-carrying conductor in a magnetic field, the respons e of a circuit to an ac voltage (signal), the working of an antenna, the propagation of radio waves in the ionosphere, etc. , are problems of electrodynamics. Optics deals with the phenomena involving light. The working of telescopes and microscopes, colours exhibited by thin films, etc. , are topics in optics. Thermodynamics, in contrast to mechanics, does not deal with the motion of bodies as a whole. Rather, it deals with systems in macroscopic equilibrium and is concerned with changes in internal energy, temperature, entropy, etc. , of the ystem through external work and transfer of heat. The efficiency of heat engines and refrigerators, the direction of a physical or * 3 You can now see that the scope of physics is truly vast. It covers a tremendous range of magnitude of physical quantities like length, mass, time, energy, etc. At one end, it studies phenomena at the very small scale of length -14 (10 m or even less) involving electrons, protons, etc. ; at the other end, it dea ls with astronomical phenomena at the scale of galaxies or even the entire universe whose extent is of the order of 26 10 m. The two length scales differ by a factor of 40 10 or even more.The range of time scales can be obtained by dividing the length scales by the –22 speed of light : 10 s to 1018 s. The range of masses goes from, say, 10–30 kg (mass of an 55 electron) to 10 kg (mass of known observable universe). Terrestrial phenomena lie somewhere in the middle of this range. Recently, the domain intermediate between the macroscopic and the microscopic (the so-called mesoscopic physics), dealing with a few tens or hundreds of atoms, has emerged as an exciting field of research. 4 Physics is exciting in many ways. To some people the excitement comes from the elegance and universality of its basic theories, from the fact that few basic concepts and laws can explain phenomena covering a large range of magnitude of physical quantities. To some others, the challenge in c arrying out imaginative new experiments to unlock the secrets of nature, to verify or refute theories, is thrilling. Applied physics is equally demanding. Application and exploitation of physical laws to make useful devices is the most interesting and exciting part and requires great ingenuity and persistence of effort. What lies behind the phenomenal progress of physics in the last few centuries? Great progress usually accompanies changes in our basic perceptions.First, it was realised that for scientific progress, only qualitative thinking, though no doubt important, is not enough. Quantitative measurement is central to the growth of science, especially physics, because the laws of nature happen to be expressible in precise mathematical equations. The second most important insight was that the basic laws of physics are universal — the same laws apply in widely different contexts. Lastly, the strategy of approximation turned out to be very successful. Most observed phenomena in daily life are rather complicated manifestations of the basic laws. Scientists recognised the importance f extracting the essential features of a phenomenon from its less significant aspects. It is not practical to take into account all the complexities of a phenomenon in one go. A good strategy is to focus first on the essential features, discover the basic principles and then introduce corrections to build a more refined theory of the phenomenon. For example, a stone and a feather dropped from the same height do not reach the ground at the same time. The reason is that the essential aspect of the phenomenon, namely free fall under gravity, is complicated by the presence of air resistance. To get the law of free all under gravity, it is better to create a situation wherein the air resistance is negligible. We can, for example, let the stone and the feather fall through a long evacuated tube. In that case, the two objects will fall almost at the same rate, giving the basic law t hat acceleration due to gravity is independent of the mass of the object. With the basic law thus found, we can go back to the feather, introduce corrections due to air resistance, modify the existing theory and try to build a more realistic P HYSICS Hypothesis, axioms and models One should not think that everything can be proved with physics and mathematics.All physics, and also mathematics, is based on assumptions, each of which is variously called a hypothesis or axiom or postulate, etc. For example, the universal law of gravitation proposed by Newton is an assumption or hypothesis, which he proposed out of his ingenuity. Before him, there were several observations, experiments and data, on the motion of planets around the sun, motion of the moon around the earth, pendulums, bodies falling towards the earth etc. Each of these required a separate explanation, which was more or less qualitative. What the universal law of gravitation says is that, if we assume that any two odies in the universe attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them, then we can explain all these observations in one stroke. It not only explains these phenomena, it also allows us to predict the results of future experiments. A hypothesis is a supposition without assuming that it is true. It would not be fair to ask anybody to prove the universal law of gravitation, because it cannot be proved. It can be verified and substantiated by experiments and observations. An axiom is a self-evident truth while a model s a theory proposed to explain observed phenomena. But you need not worry at this stage about the nuances in using these words. For example, next year you will learn about Bohr’s model of hydrogen atom, in which Bohr assumed that an electron in the hydrogen atom follows certain rules (postutates). Why did he do that? There was a large amount of spectroscopic data before him whic h no other theory could explain. So Bohr said that if we assume that an atom behaves in such a manner, we can explain all these things at once. Einstein’s special theory of relativity is also based on two postulates, the constancy of the speed f electromagnetic radiation and the validity of physical laws in all inertial frame of reference. It would not be wise to ask somebody to prove that the speed of light in vacuum is constant, independent of the source or observer. In mathematics too, we need axioms and hypotheses at every stage. Euclid’s statement that parallel lines never meet, is a hypothesis. This means that if we assume this statement, we can explain several properties of straight lines and two or three dimensional figures made out of them. But if you don’t assume it, you are free to use a different axiom and get a new geometry, as has indeed happened in he past few centuries and decades. P HYSICAL WORLD 5 theory of objects falling to the earth under gr avity. 1. 3 PHYSICS, TECHNOLOGY AND SOCIETY The connection between physics, technology and society can be seen in many examples. The discipline of thermodynamics arose from the need to understand and improve the working of heat engines. The steam engine, as we know, is inseparable from the Industrial Revolution in England in the eighteenth century, which had great impact on the course of human civilisation. Sometimes technology gives rise to new physics; at other times physics generates new technology.An example of the latter is the wireless communication technology that followed the discovery of the basic laws of electricity and magnetism in the nineteenth century. The applications of physics are not always easy to foresee. As late as 1933, the great physicist Ernest Rutherford had dismissed the possibility of tapping energy from atoms. But only a few years later, in 1938, Hahn and Meitner discovered the phenomenon of neutron-induced fission of uranium, which would serve as the bas is of nuclear power reactors and nuclear weapons. Yet another important example of physics giving rise to technology is the silicon chip’ that triggered the computer revolution in the last three decades of the twentieth century. A most significant area to which physics has and will contribute is the development of alternative energy resources. The fossil fuels of the planet are dwindling fast and there is an urgent need to discover new and affordable sources of energy. Considerable progress has already been made in this direction (for example, in conversion of solar energy, geothermal energy, etc. , into electricity), but much more is still to be accomplished. Table1. 1 lists some of the great physicists, their major contribution and the country of rigin. You will appreciate from this table the multi-cultural, international character of the scientific endeavour. Table 1. 2 lists some important technologies and the principles of physics they are based on. Obviously, these tabl es are not exhaustive. We urge you to try to add many names and items to these tables with the help of your teachers, good books and websites on science. You will find that this exercise is very educative and also great fun. And, assuredly, it will never end. The progress of science is unstoppable! Physics is the study of nature and natural phenomena. Physicists try to discover the rules hat are operating in nature, on the basis of observations, experimentation and analysis. Physics deals with certain basic rules/laws governing the natural world. What is the nature Table 1. 1 Some physicists from different countries of the world and their major contributions Name Major contribution/discovery Country of Origin Archimedes Principle of buoyancy; Principle of the lever Greece Galileo Galilei Law of inertia Italy Christiaan Huygens Wave theory of light Holland Isaac Newton Universal law of gravitation; Laws of motion; Reflecting telescope U. K. Michael Faraday Laws of electromagnetic ind uction U. K. James Clerk MaxwellElectromagnetic theory; Light-an electromagnetic wave U. K. Heinrich Rudolf Hertz Generation of electromagnetic waves Germany J. C. Bose Ultra short radio waves India W. K. Roentgen X-rays Germany J. J. Thomson Electron U. K. Marie Sklodowska Curie Discovery of radium and polonium; Studies on Poland natural radioactivity Albert Einstein Explanation of photoelectric effect; Theory of relativity Germany 6 P HYSICS Name Major contribution/discovery Country of Origin Victor Francis Hess Cosmic radiation Austria R. A. Millikan Measurement of electronic charge U. S. A. Ernest Rutherford Nuclear model of atom New Zealand Niels BohrQuantum model of hydrogen atom Denmark C. V. Raman Inelastic scattering of light by molecules India Louis Victor de Borglie Wave nature of matter France M. N. Saha Thermal ionisation India S. N. Bose Quantum statistics India Wolfgang Pauli Exclusion principle Austria Enrico Fermi Controlled nuclear fission Italy Werner Heisenberg Q uantum mechanics; Uncertainty principle Germany Paul Dirac Relativistic theory of electron; Quantum statistics U. K. Edwin Hubble Expanding universe U. S. A. Ernest Orlando Lawrence Cyclotron U. S. A. James Chadwick Neutron U. K. Hideki Yukawa Theory of nuclear forces Japan Homi Jehangir BhabhaCascade process of cosmic radiation India Lev Davidovich Landau Theory of condensed matter; Liquid helium Russia S. Chandrasekhar Chandrasekhar limit, structure and evolution of stars India John Bardeen Transistors; Theory of super conductivity U. S. A. C. H. Townes Maser; Laser U. S. A. Abdus Salam Unification of weak and electromagnetic interactions Pakistan of physical laws? We shall now discuss the nature of fundamental forces and the laws that govern the diverse phenomena of the physical world. 1. 4 FUNDAMENTAL FORCES IN NATURE* We all have an intuitive notion of force. In our experience, force is needed to push, carry or hrow objects, deform or break them. We also experience the impact o f forces on us, like when a moving object hits us or we are in a merry-goround. Going from this intuitive notion to the proper scientific concept of force is not a trivial matter. Early thinkers like Aristotle had wrong * ideas about it. The correct notion of force was arrived at by Isaac Newton in his famous laws of motion. He also gave an explicit form for the force for gravitational attraction between two bodies. We shall learn these matters in subsequent chapters. In the macroscopic world, besides the gravitational force, we encounter several kinds f forces: muscular force, contact forces between bodies, friction (which is also a contact force parallel to the surfaces in contact), the forces exerted by compressed or elongated springs and taut strings and ropes (tension), the force of buoyancy and viscous force when solids are in Sections 1. 4 and 1. 5 contain several ideas that you may not grasp fully in your first reading. However, we advise you to read them carefully to develo p a feel for some basic aspects of physics. These are some of the areas which continue to occupy the physicists today. P HYSICAL WORLD 7 Table 1. 2 Link between technology and physics TechnologyScientific principle(s) Steam engine Laws of thermodynamics Nuclear reactor Controlled nuclear fission Radio and Television Generation, propagation and detection of electromagnetic waves Computers Digital logic Lasers Light amplification by stimulated emission of radiation Production of ultra high magnetic fields Superconductivity Rocket propulsion Newton’s laws of motion Electric generator Faraday’s laws of electromagnetic induction Hydroelectric power Conversion of gravitational potential energy into electrical energy Aeroplane Bernoulli’s principle in fluid dynamics Particle accelerators Motion of charged particles in electromagnetic ields Sonar Reflection of ultrasonic waves Optical fibres Total internal reflection of light Non-reflecting coatings Thin film optical in terference Electron microscope Wave nature of electrons Photocell Photoelectric effect Fusion test reactor (Tokamak) Magnetic confinement of plasma Giant Metrewave Radio Telescope (GMRT) Detection of cosmic radio waves Bose-Einstein condensate Trapping and cooling of atoms by laser beams and magnetic fields. contact with fluids, the force due to pressure of a fluid, the force due to surface tension of a liquid, and so on. There are also forces involving charged nd magnetic bodies. In the microscopic domain again, we have electric and magnetic forces, nuclear forces involving protons and neutrons, interatomic and intermolecular forces, etc. We shall get familiar with some of these forces in later parts of this course. A great insight of the twentieth century physics is that these different forces occurring in different contexts actually arise from only a small number of fundamental forces in nature. For example, the elastic spring force arises due to the net attraction/repulsion betw een the neighbouring atoms of the spring when the spring is elongated/compressed. This net ttraction/repulsion can be traced to the (unbalanced) sum of electric forces between the charged constituents of the atoms. In principle, this means that the laws for ‘derived’ forces (such as spring force, friction) are not independent of the laws of fundamental forces in nature. The origin of these derived forces is, however, very complex. At the present stage of our understanding, we know of four fundamental forces in nature, which are described in brief here : 8 P HYSICS Albert Einstein (1879-1955) Albert Einstein, born in Ulm, Germany in 1879, is universally regarded as one of the greatest physicists of all time.His astonishing scientific career began with the publication of three path-breaking papers in 1905. In the first paper, he introduced the notion of light quanta (now called photons) and used it to explain the features of photoelectric effect that the classical wave th eory of radiation could not account for. In the second paper, he developed a theory of Brownian motion that was confirmed experimentally a few years later and provided a convincing evidence of the atomic picture of matter. The third paper gave birth to the special theory of relativity that made Einstein a legend in his own life time.In the next decade, he explored the consequences of his new theory which included, among other things, the mass-energy equivalence enshrined in his famous equation E = mc2. He also created the general version of relativity (The General Theory of Relativity), which is the modern theory of gravitation. Some of Einstein’s most significant later contributions are: the notion of stimulated emission introduced in an alternative derivation of Planck’s blackbody radiation law, static model of the universe which started modern cosmology, quantum statistics of a gas of massive bosons, and a critical analysis of the foundations of quantum mechanics.Th e year 2005 was declared as International Year of Physics, in recognition of Einstein’s monumental contribution to physics, in year 1905, describing revolutionary scientific ideas that have since influenced all of modern physics. 1. 4. 1 Gravitational Force The gravitational force is the force of mutual attraction between any two objects by virtue of their masses. It is a universal force. Every object experiences this force due to every other object in the universe. All objects on the earth, for example, experience the force of gravity due to the earth. In particular, gravity governs the motion of the moon and artificial satellites around he earth, motion of the earth and planets around the sun, and, of course, the motion of bodies falling to the earth. It plays a key role in the large-scale phenomena of the universe, such as formation and evolution of stars, galaxies and galactic clusters. 1. 4. 2 Electromagnetic Force Electromagnetic force is the force between charged parti cles. In the simpler case when charges are at rest, the force is given by Coulomb’s law : attractive for unlike charges and repulsive for like charges. Charges in motion produce magnetic effects and a magnetic field gives rise to a force on a moving charge. Electric nd magnetic effects are, in general, inseparable – hence the name electromagnetic force. Like the gravitational force, electromagnetic force acts over large distances and does not need any intervening medium. It is enormously strong compared to gravity. The electric force between two protons, for example, 36 is 10 times the gravitational force between them, for any fixed distance. Matter, as we know, consists of elementary charged constituents like electrons and protons. Since the electromagnetic force is so much stronger than the gravitational force, it dominates all phenomena at atomic and molecular scales. (The other two forces, as we hall see, operate only at nuclear scales. ) Thus it is mainly the elec tromagnetic force that governs the structure of atoms and molecules, the dynamics of chemical reactions and the mechanical, thermal and other properties of materials. It underlies the macroscopic forces like ‘tension’, ‘friction’, ‘normal force’, ‘spring force’, etc. Gravity is always attractive, while electromagnetic force can be attractive or repulsive. Another way of putting it is that mass comes only in one variety (there is no negative mass), but charge comes in two varieties : positive and negative charge. This is what makes all the difference.Matter is mostly electrically neutral (net charge is zero). Thus, electric force is largely zero and gravitational force dominates terrestrial phenomena. Electric force manifests itself in atmosphere where the atoms are ionised and that leads to lightning. P HYSICAL WORLD 9 Satyendranath Bose (1894-1974) Satyendranath Bose, born in Calcutta in 1894, is among the great Indian physicists who made a fundamental contribution to the advance of science in the twentieth century. An outstanding student throughout, Bose started his career in 1916 as a lecturer in physics in Calcutta University; five years later he joined Dacca University.Here in 1924, in a brilliant flash of insight, Bose gave a new derivation of Planck’s law, treating radiation as a gas of photons and employing new statistical methods of counting of photon states. He wrote a short paper on the subject and sent it to Einstein who immediately recognised its great significance, translated it in German and forwarded it for publication. Einstein then applied the same method to a gas of molecules. The key new conceptual ingredient in Bose’s work was that the particles were regarded as indistinguishable, a radical departure from the assumption that underlies the classical MaxwellBoltzmann statistics.It was soon realised that the new Bose-Einstein statistics was applicable to particles with integers spins, and a new quantum statistics (Fermi-Dirac statistics) was needed for particles with half integers spins satisfying Pauli’s exclusion principle. Particles with integers spins are now known as bosons in honour of Bose. An important consequence of Bose-Einstein statistics is that a gas of molecules below a certain temperature will undergo a phase transition to a state where a large fraction of atoms populate the same lowest energy state.Some seventy years were to pass before the pioneering ideas of Bose, developed further by Einstein, were dramatically confirmed in the observation of a new state of matter in a dilute gas of ultra cold alkali atoms – the Bose-Eintein condensate. If we reflect a little, the enormous strength of the electromagnetic force compared to gravity is evident in our daily life. When we hold a book in our hand, we are balancing the gravitational force on the book due to the huge mass of the earth by the ‘normal force’ provided by our hand. The latter is nothing but the net electromagnetic force between the charged constituents of our hand and he book, at the surface in contact. If electromagnetic force were not intrinsically so much stronger than gravity, the hand of the strongest man would crumble under the weight of a feather ! Indeed, to be consistent, in that circumstance, we ourselves would crumble under our own weight ! 1. 4. 3 Strong Nuclear Force The strong nuclear force binds protons and neutrons in a nucleus. It is evident that without some attractive force, a nucleus will be unstable due to the electric repulsion between its protons. This attractive force cannot be gravitational since force of gravity is negligible compared to the electric force.A new basic force must, therefore, be invoked. The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength. It is charge-independent and acts equally between a proton and a proton, a neutron a nd a neutron, and a proton and a neutron. Its range is, however, extremely small, –15 of about nuclear dimensions (10 m). It is responsible for the stability of nuclei. The electron, it must be noted, does not experience this force. Recent developments have, however, indicated that protons and neutrons are built out of still more elementary constituents called quarks. . 4. 4 Weak Nuclear Force The weak nuclear force appears only in certain nuclear processes such as the ? -decay of a nucleus. In ? -decay, the nucleus emits an electron and an uncharged particle called neutrino. The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic forces. The range of weak nuclear force is exceedingly small, of the order of 10-16 m. 1. 4. 5 Towards Unification of Forces We remarked in section 1. 1 that unification is a basic quest in physics. Great advances in physics often amount to unification of different 10 P HYSICS Tab le 1. Fundamental forces of nature Name Relative strength Range Operates among Gravitational force 10 –39 Infinite All objects in the universe Weak nuclear force 10–13 Very short, Sub-nuclear size ( ? –16 m) 10 Some elementary particles, particularly electron and neutrino Electromagnetic force 10–2 Infinite Charged particles Strong nuclear force 1 Short, nuclear size ( ? –15 m) 10 Nucleons, heavier elementary particles theories and domains. Newton unified terrestrial and celestial domains under a common law of gravitation. The experimental discoveries of Oersted and Faraday showed that electric and magnetic phenomena are in general nseparable. Maxwell unified electromagnetism and optics with the discovery that light is an electromagnetic wave. Einstein attempted to unify gravity and electromagnetism but could not succeed in this venture. But this did not deter physicists from zealously pursuing the goal of unification of forces. Recent decades have seen much progress on this front. The electromagnetic and the weak nuclear force have now been unified and are seen as aspects of a single ‘electro-weak’ force. What this unification actually means cannot be explained here. Attempts have been (and are being) made to unify the electro-weak and the trong force and even to unify the gravitational force with the rest of the fundamental forces. Many of these ideas are still speculative and inconclusive. Table 1. 4 summarises some of the milestones in the progress towards unification of forces in nature. 1. 5 NATURE OF PHYSICAL LAWS Physicists explore the universe. Their investigations, based on scientific processes, range from particles that are smaller than atoms in size to stars that are very far away. In addition to finding the facts by observation and experimentation, physicists attempt to discover the laws that summarise (often as mathematical quations) these facts. In any physical phenomenon governed by different forc es, several quantities may change with time. A remarkable fact is that some special physical quantities, however, remain constant in time. They are the conserved quantities of nature. Understanding these conservation principles is very important to describe the observed phenomena quantitatively. For motion under an external conservative force, the total mechanical energy i. e. the sum of kinetic and potential energy of a body is a constant. The familiar example is the free fall of an object under gravity. Both the kinetic energy

Eastman Kodak

ACC 230 Week 4 Checkpoint Nov 15, 2012 Chapter 3, Page 111, Problem 3. 16b Eastman Kodak Eastman Kodak appears to be profitable even though their net income has decreased. They show an increase in sales since from 2002 to 2004, but their operating costs also increased by 15. 3 % from 2002 to 2003. The increase in sales was primarily through acquisitions and the impact of foreign exchange rates on their holdings. Kodak’s largest holding, Digital and Film Imaging Systems, experienced a 1% decrease during this period. In a comparative analysis of the years 2003 and 2004, Kodak increased their current assets and decreased total assets.This reflects the disposal of assets such as equipment, plant and property, and complete discontinuance of certain operations. This decrease in total assets can be seen as a prudent move in their restructuring process. They also decreased their number of employees in 2004 and cut back on their advertising expense. Kodak has decreased total liabilitie s by 4%. This is the result of decreases in short term and long term borrowings. By paying off debt, the company is improving its overall financial position. Kodak also sows a positive net profit margin even though they show a loss in 2004.Kodak’s other income in 2004 resulted from settlements in favor of Kodak which will not recur in future periods. There is a drop in total shareholder’s equity, but they have shown an increase in the equity percentage held by the company. This seems to be the result of $104k more shares in 2004 than in 2003, since the total number of shares outstanding remained constant in 2003 and 2004. Retained earnings on stock increased in 2004. The company seems to be in good standing from a profitability viewpoint. If they continue with the changes to the company’s structure, they should be able to stay in a profitable income margin.

Totalitarionism essays

Totalitarionism essays Over the years there have been many leaders. Three of the most known are Benito Mussolini, Josef Stalin, and Adolf Hitler. These three were dictators and had a totalitarian government. This essay will discuss their rise to power, public sentiment, and accomplishments. Also it will discuss their crimes and what kind of legacy they left. The three men came to power in almost the same way. Mussolini started a Fascist party and took power. Stalin was part of a Communist committee that ran the country after Lenin died. He used his friends in the committee to get him to power. After he became dictator he had all the people who got him to power killed. Hitler started the Nazi party, which is a Fascist group. With his influence he was voted to power. He too had the people who voted him to power killed. That was known as the Night of Long Knives. The public felt the same for Stalin and Hitler but Mussolini was different. Mussolini was a great public speaker. Whenever he spoke the crowds would cheer. In the beginning Mussolini was liked by the people but in the end the public ended up killing him and hanging him. The people loved Stalin. His people considered him a great man. They wept for him when he died of an aneurysm. The public followed Hitlers ideas and praised him. In the end he killed himself. Each of these leaders made different accomplishments for their country. Mussolini gave the people what they wanted to hear. He did not do a lot of good though. Stalin nationalized the industry and made it spread throughout the world. He ended the civil war. Hitler did a very good thing for his country. He got his country out of the great depression. This was a great accomplishment. He also strengthened the army. As with their accomplishments these leaders had committed many crimes. Mussolini had people killed and censored all of the news so it would not incrimina ...

Gigantopithecus - Facts and Figures

Gigantopithecus - Facts and Figures Name: Gigantopithecus (Greek for giant ape); prounced jie-GAN-toe-pith-ECK-us Habitat: Woodlands of Asia Historical Epoch: Miocene-Pleistocene (six million to 200,000 years ago) Size and Weight: Up to nine feet tall and 1,000 pounds Diet: Probably omnivorous Distinguishing Characteristics: Large size; large, flat molars; four-footed posture About Gigantopithecus The literal 1,000-pound gorilla sitting in the corner of a natural history museum, the appropriately named Gigantopithecus was the largest ape that ever lived, not quite King Kong-sized but, at up to half a ton or so, much bigger than your average lowland gorilla. Or, at least, thats the way this prehistoric primate has been reconstructed; frustratingly, practically everything we know about Gigantopithecus is based on its scattered, fossilized teeth and jaws, which first came to the worlds attention when they were sold in Chinese apothecary shops in the first half of the 20th century. Paleontologists arent even sure how this colossus moved; the consensus is that it must have been a ponderous knuckle-walker, like modern gorillas, but a minority opinion holds that Gigantopithecus may have been capable of walking on its two hind feet. Another mysterious thing about Gigantopithecus is when, exactly, it lived. Most experts date this ape from Miocene to mid-Pleistocene eastern and southeastern Asia, about six million to one million years B.C., and it may have survived in small populations until as late as 200,000 or 300,000 years ago. Predictably, a small community of cryptozoologists insists that Gigantopithecus never went extinct, and persists in the present day, high up in the Himalayan Mountains, as the mythical Yeti, better known in the west as the Abominable Snowman! (Rest assured that no reputable scientists subscribe to this theory, which is supported by absolutely no compelling material or eyewitness evidence.) As fearsome as it must have looked, Gigantopithecus seems to have been mostly herbivorouswe can infer from its teeth and jaws that this primate subsisted on fruits, nuts, shoots and, just possibly, the occasional small, quivering mammal or lizard. (The presence of an unusual number of cavities in Gigantopithecus teeth also points to a possible diet of bamboo, much like that of a modern Panda Bear.) Given its size when fully grown, an adult Gigantopithecus would not have been an active target of predation, though the same cant be said for sick, juvenile or aged individuals, which figured on the lunch menu of various tigers, crocodiles and hyenas. Gigantopithecus comprises three separate species. The first and largest, G. blacki, lived in southeastern Asia starting in the middle Pleistocene epoch and shared its territory, toward the end of its existence, with various populations of Homo erectus, the immediate precursor of Homo sapiens. The second, G. bilaspurensis, dates to six million years ago, during the Miocene epoch, about the same early time frame as the oddly named G. giganteus, which was only about half the size of its G. blacki cousin.

Foundations of Knowledge and Professional Skills Assignment

Foundations of Knowledge and Professional Skills - Assignment Example element of surprise in these two organizations the author gives a case where the film crew was shooting a dramatic slaughter scene on the top of the floor. The electricity electrocutes the victim, while failing into a hot tub. However, they failed to account for displacement. When the actor failed into the tub, the water overflowed, spreading over the floor. The floor shorted the electricity in the entire mansion, halting the production. On the case of SWAT police, he brings out a case where the police had prepared to execute a search warrant on suspected drug house. The officer on the team had reviewed pictures film and diagrams of the location. They sketched the route to follow during the entry and agreed on their distribution inside the location (Edward, 2009, p.382). The wall and rooms were not in expected configuration. According to cunha, surprise is a break in the expectation that arise from a situation that are not expected or do not advance as planned (Baker 2007). It encompasses unanticipated element and draws attention from standard progression of work. Surprises are interesting for they show the various way an organization faces uncertainty and adapts. Surprise has been characterized into various group based on their source and outcomes. Both events processes generate them. Cuhn et al (2003, P.322) argues that they can emerge from simple situation, or a complicated system. The consequences of surprise can be negative or positive at their most negative they can constitute to a cosmology event as described by Mann gulch blaze. The positive consequences are where the outcome of surprises engages the organization members with situation coupled with recognition of need for change. No matter the source of the surprise the organization member need to response in a manner that enables their work to continue. Organization is increasingly facing surprise as enumerated by Barley (2006, p.88). It is therefore very important to understand what make organization