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[Page 1] Topic Covered Plancess Concepts PlancEssential Tips & Tricks, Facts, Notes, Misconceptions, Key Take Aways, Problem Solving Tactics Questions recommended for revision By Top 100 IIT-JEE rankers & Senior Faculty of Premier Institutes. PHYSICS F O R J E E M A I N & A D V A N C E D Class 11 2017-18 5000+ Illustrations and Solved Examples Exhaustive Theory (Now Revised) 2500 Problems + 1000 (New) of previous 35 years of AIEEE (JEE Main) and IIT-JEE (JEE Adv) 9000+ Problems based on latest JEE pattern Detailed Solutions of all problems available Formula Sheet Simple Harmonic Motion and Elasticity SECOND EDITION [Page 2] PLANCESS CONCEPTS 8. S I M P L E H A R M O N I C M O T I O N A N D E L A S T I C I T Y SIMPLE HARMONIC MOTION 1. INTRODUCTION There are so many examples of oscillatory or vibrational motion in our world. E.g. the vibrations of strings in a guitar or a sitar, the vibrations in the speakers of a music system, the to and fro motion of a pendulum, vibration in a suspension bridge as a vehicle passes on it, the oscillations in a tall building during an earthquake etc. Simple harmonic motion (SHM) is a type of oscillatory or vibrational motion. Every kind of oscillation or vibration of a particle or a system is not necessarily simple harmonic. The particle executing SHM like any other oscillatory motion has a variable acceleration, but this variation is different in different kinds of oscillations. The study of SHM is very useful and forms an important tool in understanding the characteristics of sound and light waves and alternating currents. Any oscillatory motion which is not simple harmonic can be expressed as a superposition of several simple harmonic motions of different frequencies. 2. PERIODIC AND OSCILLATORY MOTION Periodic Motion: A motion which repeats itself after equal intervals of time is called periodic motion. Oscillatory Motion: A body is said to possess oscillatory or vibratory motion if it moves back and forth repeatedly about a mean position. For an oscillatory motion, a restoring force is required. Examples of Periodic and Oscillatory motion are revolution of earth around sun and motion of bob of a simple pendulum respectively. All Oscillatory motions are periodic but all Periodic motions need not be oscillatory. A body experiencing force n