ENGINEERING MECHANICS: STATICS AND DYNAMICS

1 ENGINEERING mechanics : STATICS AND DYNAMICSDr. TayalPh. ProfessorDepartment of Mechanical EngineeringDelhi College of ENGINEERING (Now Deemed University)DelhiCompiled byDeeksha TayalUMESH PUBLICATIONSP ublishers of ENGINEERING and Computer Books4230/1, Ansari Road, Daryaganj, Delhi-110 002 Phones: (O) 32957898, 43028013 ENGINEERING mechanics : STATICS and by:UMESH PUBLICATIONS4230/1, Ansari Road, Daryaganj, Delhi-110 002 Phone : 32957898, 43028013 PublishersFirst Edition : 1989 Tenth Edition : 1999 Eleventh Edition : 2000 Thirteenth Edition.

2 2005 Fourteenth Edition : 2011 (Revised and Enlarged)All rights reserved, No part of this publication may be reproduced, translated ortransmitted (except for review or criticism), without the written permission of : 978-93-80117-38-6 Price : Rs Typeset by:SARA Assignments, Shahdara, Delhi-110 at:Narula Printers, Navin Shahdara, Delhi-110 to the Fourteenth EditionIt gives me a great pleasure to present the Fourteenth Edition of this book on EngineeringMechanics. I express my gratitude for the wide acceptability of the book by the academics aswell as student community and it gives me deep sense of satisfaction.

3 In this new edition, a newchapter on Shear Force and Bending Moment has been added. This topic is included to meetthe current requirements of some again, request for the suggestions and comments for the improvement of the TAYALJ anuary, 2011 mechanics is essentially a deductive science based on a few fundamental principles and hasvectorial character. This book has been written with a view to emphasize the vectorial characterof mechanics in such a manner so that the material presented may not require any previousknowledge of mathematics beyond elementary calculus.

4 For this reason, products and derivativesof vectors are not used. A chapter on the Review of Vectors and Forces in Space , however, hasbeen included as an appendix to introduce the vector approach of the subject. This chapter canbe covered before going on the mechanics of coplanar system of is a well recognised fact that the teaching of the first course in a subject should be basedon a text book. A systematic, consistent and clear presentation of concepts through explanatorynotes and figures and worked out problems are the main requirements of a text book.

5 This bookhas been written to meet such requirements. Merely stating the principles and explaining theconcepts is not enough; these are to be identified as applicable to the various problems whichmay appear to be strangely different. With this objective, a large number of worked-out problemshave been included in this book. In the most worked-out problems, free-body diagrams have beenseparately drawn with the coordinate axes shown. The equations of equilibrium or of motion,as applicable, have been indicated.

6 Inertia forces have also been clearly identified in a methods of solution to a number of problems have given or indicated to explain thecomparative merits of the concepts and solution procedures involved. In fact, skill throughrepetition may be as much true here as in occult am grateful to many of my faculty colleagues and numerous students at Delhi College ofEngineering, Delhi (now Deemed University) who have contributed significantly by way ofconstructive and useful discussions.

7 The patience of the family members and the encouragementby friends is gratefully am also tankful to the publishers who have taken keen interest throughout the preparationof the may best efforts, it is possible that some unintentional errors may have escaped myattention. I would gratefully acknowledge if any of these is pointed out. Also, any suggestionsand comments for further improvement of the book would be gratefully received and K. TAYALP reface to the First EditionPreface to the Fourteenth EditionviPrefacevii1.

8 INTRODUCTION1 ENGINEERING mechanics Idealization of Bodies Basic Concepts Fundamental Principles Systems of Units 42. CONCURRENT FORCES IN A PLANE7 Force Scalar and Vector Addition of Two forces: Parallelogram Law Concept of the Resultant of Several Forces Resultant of Several Concurrent Coplanar Forces: Polygon Law Resolution of a Force into Components Resultant of a Several Concurrent Coplanar Forces bySumming Rectangular Components (Method of Projections) Equations of Equilibrium for a System of Concurrent Forces in a Plane Constraint, Action and Reaction Types of Supports and Support Reactions Diagram (a) Equilibrium of a Body Subjected to Two Forces (Two Force Body) (b)

9 Equilibrium of a Body Subjected to Three Forces of a Force of Varignon of Equilibrium 49 Problems56 ContentsxCONTENTS3 . PARALLEL FORCES IN A PLANE59 Parallel Forces Resultant of Two Parallel Forces Acting in the Same Direction Resultant of Two Unequal Parallel Forces Acting in Opposite Directions Two Equal Parallel Forces Acting in Opposite Directions; Couple The Resolution of a Force into a Force and a Couple Equivalent System of Forces General Case of Parallel Forces in a Plane Distributed Forces in a Plane Hydrostatic Pressure: Forces on Submerged Surfaces 75 Problems804.

10 CENTROID, CENTRE OF MASS AND CENTREOF GRAVITY82 Introduction Centre of Gravity of a Body: Determination by the Method of Moments Concept of Centroid Centroid Two Dimensional Body Determination of Centroid and Centre of Gravity: Integration Method Centroid of a Composite Plane Figure Theorems of Pappus and Guldinus 103 Problems1045 . GENERAL CASE OF FORCES IN A PLANE108 General Case of Forces Acting in a Plane: Equations of Equilibrium 108 Problems1186.