Mechanical Waves Mechanical wave is a disturbance that

機械波 Mechanical Waves • Mechanical wave is a disturbance that travels through some material or substance called the medium for wave. • Transverse wave is the wave that the displacement of the medium are perpendicular or transverse to the direction of travel of the wave along the medium • Longitudinal wave is the wave that the motions of particles is the same as the direction of wave.

Wave Equation

Mathematical Description of a Wave sinusoidal wave moving in +x-direction Phase

Energy in Wave Motion The instantaneous rate of doing work at the point x and time t is For sinusoidal wave with wave function given as

Maximum Power average power, sinusoidal wave on a string

Average intensity inverse-square law for intensity

Wave Interference Boundary Conditions and Superposition

Overlap of two wave pulses

standing wave on a string, fixed end at x = 0

Normal Modes of a String

Sound Waves Sound is a longitudinal wave in a medium Audible range of human ear is 20 to 20000 Hz

Gauge pressure

Gauge pressure

In a sinusoidal sound wave the max pressure variations are 3. 0*10 -2 Pa above the atmospheric pressure. Find the max displacement if frequency is 1000 Hz. Given speed of sound is 344 m/s and bulk modulus is 1. 42*105 Pa

The Anatomy of Human Ear A eardrum = 43 mm 2 A stirrup = 3. 2 mm 2 V fluid =1500 m/s

Sound Velocity and Gauge Pressure intensity of a sinusoidal sound wave definition of sound intensity level

http: //www. sfu. ca/sca/Manuals/ZAAPf/e/equal_loud_cont. html

Basic Principle of Doppler Flowmeter

16. 8 The Doppler effect Moving listener and stationary source

Moving source and moving listener

People used Doppler flow meter to measure the blood flow rates. The speed of sound in blood is known to be 1570 m/s and a typical red blood cell has a radius of 5μm. Please estimate what would be the frequency for the flow meter? If the frequency shift measured by the Doppler flow meter is 100 Hz (the meter was operated at 107 Hz), please find the average velocity of blood flow. 1. 5 cm/s

Shack Wave (Sonic Boom) http: //en. wikipedia. org/wiki/Sound_barrier

橫波(transverse wave)彈性體所產生之形 變為剪應變(shear strain)

縱波(longitudinal wave)彈性體所產生之 形變為拉伸應變(tensile strain)恢復力為 拉伸應力(tensile stress)