南开大学：《力学》课程教学资源（PPT课件，英文讲稿）Chapter 6 Vibration and wave

Chapter6Vibration and wave

Chapter 6 Vibration and wave

IntroductionOscillatorOne kind of motionApplication of Newton's LawWaveElectromagnetism.Optics,ModernBut its result isvery important.physics(Quantum Mechanics)energyWhytransportinformationAll starts from

Introduction: One kind of motion. Oscillator Application of Newton’s Law. Wave But its result is very important. Why information energy transport All starts from.  Electromagnetism,Optics,Modern physics(Quantum Mechanics)

S1.Harmonic oscillation1-1 Simple harmonic motionMass on a springf =-kxmx=-kxkx+-x=0mX+ 0?x =0 一 Differential e.q.intrinsic

f = −kx §1. Harmonic oscillation m x = −kx •• + = 0 •• x m k x 0 2 + = •• x  x 1-1 Simple harmonic motion Mass on a spring. Differential e.q. intrinsic x o

Simple pendulumwPendulumCompound pendulum- mg sin ll = IβO!0-mgsinθ=moe.C-mg0=10Xmgl0+0=0mgIsin 0~～00+0°0=0山

− mg sinl c = I •• − mg sin = m •• − mgl c = I + = 0 ••   I mgl c Pendulum Simple pendulum Compound pendulum  sin  x o  mg L C O C 0 2 + = ••   

Pure rotationm DefinitionSPhysical quantity:+02g=0OExample:mmglcmgrc02c.11I0RI, =mR2=I +m(R-r)0I =I +rm=mR2-m(R-r)-rm

0 2 + = ••    Physical quantity:   Definition. Pure rotation Example: I mgr I mglc c = = 2  2 2 0 ( ) ' c c I = mR = I + m R − r I o I c r m mR m R r c r c m 2 2 2 2 = + = − ( − ) − R o' o c m rc 