###### Questions and Problems in School Physics

### Questions and Problems in School Physics

###### A Dialogue Approach

# About the Book

**Questions and Problems in School Physics.**

It can safely be asserted that no student preparing for an entrance examination in physics, for admission to an engineering institute has yet opened a book similar to this one. Employing the extremely lively form of dialogue, the authors were able to comprehensively discuss almost all the subjects in the syllabus, especially questions usually considered difficult to understand. The book presents a detailed analysis of common mistakes made by students taking entrance examinations in physics. Students will find this to be an exceptionally clear and interesting textbook which treats of complicated problems from various viewpoints and contains a great many excellent illustrations promoting a deeper understanding of the ideas and concepts involved.

The authors (Lev Tarasov and Aldina Tarasova : lecturers of the Moscow Institute of Electronics Engineering, Chandra Shekhar Kumar : alumnus of Indian Institute of Technology Kanpur) are well acquainted with the general level of training of students seeking admission to engineering institutes; they have years of experience in conducting entrance examinations. The expert knowledge of the authors, in conjunction with the lively and lucid presentation, has made this a very useful study guide for students preparing for physics examinations.

This book was planned as an aid to students preparing for an entrance examination in physics for admission to an engineering institute. It has the form of a dialogue between the author (the TEACHER) and an inquisitive reader (the STUDENT). This is exceptionally convenient for analyzing common errors made by students in entrance examinations, for reviewing different methods of solving the same problems and for discussing difficult questions of physical theory. A great many questions and problems of school physics are dealt with. Besides, problems are given (with solutions) for home study. Most of the questions and problems figured in the entrance examinations of the Moscow Institute of Electronics Engineering in the years 1964-66 and Indian Institute of Technology in the years 1990-2020.

An analysis of mistakes made by students is always instructive. Attention can be drawn to various aspects of the problem, certain fine points can be made, and a more thorough understanding of the fundamentals can be reached. Such an analysis, however, may prove to be very difficult. Though there is only one correct answer, there can be a great many incorrect ones. It is practically impossible to foresee all the incorrect answers to any question; many of them remain concealed forever behind the distressing silence of a student being orally examined. Nevertheless, one can point out certain incorrect answers to definite questions that are heard continually. There are many questions that are almost inevitably answered incorrectly. This book is based mainly on these types of questions and problems.

We wish to warn the reader that this is by no means a textbook embracing all the items of the syllabus. He will not find here a systematic account of the subject matter that may be required by the study course in physics. He will find this text to be perhaps more like a freely told story or, rather, a freely conducted discussion. Hence, it will be of little use to those who wish to begin their study of physics or to systematize their knowledge of this science. It was intended, instead, for those who wish to increase their knowledge of physics on the threshold of their examinations.

Our ideal reader, as we conceive him, has completed the required course in school physics, has a good general idea of what it is all about, remembers the principal relationships, can cite various laws and has a fair knowledge of the units employed. He is in that suspended state in which he is no longer a secondary school student and has not yet become a full-fledged student of an institute. He is eager, however, to become one. If this requires an extension of his knowledge in physics, our book can help him.

Primarily, we hope our book will prove that memorizing a textbook (even a very good one) is not only a wearisome business, but indeed a fruitless one. A student must learn to think, to ponder over the material and not simply learn it by heart. If such an understanding is achieved, to some extent or other, we shall consider our efforts worthwhile.

Employing the extremely lively form of dialogue between the TEACHER and an inquisitive READER, this book comprehensively discusses almost all the subjects in school physics, especially questions usually considered difficult to understand.

In this edition, the entire manuscript was typeset using the **LaTeX** document processing system originally developed by Leslie Lamport, based on TeX typesetting system created by Donald Knuth. The typesetting software used the XeLaTeX distribution.

I am grateful for this opportunity to put the materials into a consistent format, and to correct errors in the original publication that have come to my attention. The process of compiling this book has given me an incentive to improve and extend the text, dialogue, concepts, problems, solutions, layout, to double check almost all of the mathematical rendering, to correct all known errors, to improve the original illustrations by redrawing them with Till Tantau's marvellous **TikZ**, to include new diagrams. Thus the book now appears in a form that we hope will remain useful for at least another generation.

#### Table of Contents

- 1. Can You Analyze Graphs Representing the Kinematics of Straight-Line Motion ?
- 2. Can You Show The Forces Applied To A Body?
- 3. Can You Determine The Friction Force?
- 4. How Well Do You Know Newton’s Laws Of Motion ?
- 5. How Do You Go About Solving Problems In Kinematics ?
- 6. How Do You Go About Solving Problems In Dynamics ?
- 7. Are Problems In Dynamics Much More Difficult To Solve If Friction Is Taken Into Account ?
- 8. How Do You Deal With Motion In A Circle ?
- 9. How Do You Explain The Weightlessness Of Bodies ?
- 10. Can You Apply The Laws Of Conservation Of Energy And Linear Momentum ?
- 11. Can You Deal With Harmonic Vibrations ?
- 12. What Happens To A Pendulum In A State Of Weightlessness ?
- 13. Can You Use The Force Resolution Method Efficiently ?
- 14. What Do You Know About The Equilibrium Of Bodies ?
- 15. How Do You Locate The Centre Of Gravity ?
- 16. Do you know Archimedes’ principle ?
- 17. Is Archimedes’ Principle Valid In A Spaceship ?
- 18. What Do You Know About The Molecular-Kinetic Theory Of Matter ?
- 19. How Do You Account For The Peculiarity In The Thermal Expansion Of Water ?
- 20. How Well Do You Know The Gas Laws ?
- 21. How Do You Go About Solving Problems On Gas Laws ?
- 22. Let Us Discuss Field Theory
- 23. How Is An Electrostatic Field Described ?
- 24. How Do Lines Of Force Behave Near The Surface Of A Conductor ?
- 25. How Do You Deal With Motion In A Uniform Electrostatic Field ?
- 26. Can You Apply Coulomb’s Law ?
- 27. Do You Know Ohm’s Law ?
- 28. Can A Capacitor Be Connected Into A Direct-Current Circuit ?
- 29. Can you compute the resistance of a branched portion of a circuit ?
- 30. Why Did The Electric Bulb Burn Out ?
- 31. Do You Know How Light Beams Are Reflected And Refracted ?
- 32. How Do You Construct Images Formed By Mirrors And Lenses ?
- 33. How Well Do You Solve Problems Involving Mirrors And Lenses ?

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