Two new chapters on eneral Themodynamic Relations and Variable Specific Heat have been Added.The mistake which had crept in have been elinimated.we wish to express our sincere thanks to numerous professors and students,both at home and abroad,for sending their valuable suggestions and also for recommending the book to their students and friends.

The present book on Elements of Mechanical Engineering is meant for the engineering students of all branches at their first year level.It covers the new syllabus of panjab Technical University,Jalandhar.However,it shall be useful to students of other Universities also.The book covers the basic principles of Thermodynamics,zeroth law of Thermodynamics and the concept of temperature in the first chapter.