PPT-Today: Finish Vibrations and Waves (Ch 19)

Sound Ch 20 Preliminaries What is the origin of sound Vibrations of objects eg of a string of a reed of vocal cords Usually the small vibration stimulates vibration of a larger object . And for as many years wall and ceiling contractors have tried to fulfill their obligations by providing the finish conditions envisioned but not truly described As a means of resolving a common problem in 1990 four major trade associations concerned Pages 8-12. 1. . A rhythmic . disturbance that carries energy but . not matter.. 2. A type of wave that can travel only through matter.. 3. Material through which a wave travels. This can be a solid, liquid, or a gas.. WAves. A wiggle in time is a vibration. .. A wiggle in space and time is a wave.. A vibration can exist in one location, a wave cannot. A wave must travel from one place to another.. Vibration of a Pendulum. By Rhett Price. Speed of Sound . Speed of sound depends on density. Correlation between speed and density. Not as fast as light speed. Also affected by pressure and temperature. Positive correlation between them. Doppler Effect. ~apparent change in frequency of a wave due to the motion of the source of the wave.. If the object is moving towards the observer the frequency will appear to increase. If the object is moving away from the observer the frequency will appear to decrease. Periodic Motion – any repeated motion with regular time intervals. Simple Harmonic Motion – vibration about an equilibrium position in which a restoring force is proportional to the displacement from equilibrium . Waves transfer energy!. A wave does not carry matter . It only moves matter as it travels through it.. Waves. Compression (longitudinal) waves . are waves in which the particles of the medium move in a direction . Before the waves are made the particles are same distance apart. While waves moves through the medium the particles . compress. together, then they spread further apart (stretched areas)- . rarefaction.. A wave is any disturbance that transmits energy through matter or empty space.. Energy can be carried away from it’s source by a wave. As a wave travels, it does work on everything in it’s path. Wave. Repeating disturbance or movement. Carries energy through matter and space. Vibrations. Anything that moves in a rhythmic patter. Up and down. Back and forth. What is a Wave. All waves are produced when something vibrates. Learning Objectives. Understand what are vibrations and the risks they cause. Recognize symptoms and effects . Hand arm and whole body vibrations. Preventing and reducing injury. What is Vibration? . - Jon . Kabat. -Zinn. Waves are moving . energy. !. Most waves wind-driven. Moving energy along ocean/air interface:. Wind main disturbing force. Boundary between and within fluids with different densities. ). Looking ahead: Midterm 2 Nov 18. (on . Chs. 9, 11, 13, 14, 15, 19, 20, 22 probably). . Vibrations. Some Preliminaries . Vibration = oscillation = anything that has a back-and-forth to it . Eg. . Draw a pen back and forth over the same line, repeatedly:. The Scottish physicist James Clerk Maxwell (1831–1879) was the first person to truly understand the fundamental nature of light. . He proved in 1865 that an electromagnetic disturbance should propagate in free space with a speed equal to that of light..