Er"K) 5Aeto-ok- C4)c4/-0. t -otavolhat ( LINI(1. Ns. / hvligr freikia7. 1:713c44>s.<1 A C cfrer 467vi-sf= woe, ejtv,,aloer

Transcription

1 Ns. LINI(1 pvtraitte,) CAC- Licuye TivettPlic-% V( (fx ana )( (c r dr 41.04,/ 1:713c44>s.<1 A C cfrer 467vi-sf=1.1 5 t -otavolhat ( 5Aeto-ok- C4)c4/-0 ' woe, ejtv,,aloer Er"K) / hvligr freikia7

2 16 Traveling Waves kickp5(,(0 uo ' This si:ricsr is "catching a wave." At the same time, he's, seeing light waves and hearing sound waves. IN THIS CHAPTER, you will learn the basic properties of traveling waves. What is a wave? A ave is a disturbance traveling through a medium. In a transverse wave, the displacement is perpendicular to the direction of travel. In a longitudinal wave, the displacement is parallel to the direction of travel. Transverse was e.4m M IIIKM Longitudinal wave Do waves carry energy? They do. The rate at which a wave delivers energy to a surface is the intensity of the wave. For sound waves, well use a logarithmic decibel scale to characterize the loudness of a sound. Intensity is decreasing What are some wave properties? A wave is characterized by: Wave speed: How fast it travels through the medium. Wavelength: The distance between two neighboring crests. pe Frequency: The number of oscillations per second. Amplitude: The maximum displacement. (( LOOKING BACK Sections Properties of simple harmonic motion Are sound and light waves? Yes! Very important waves. Sound waves are longitudinal waves. Light waves are transverse waves. The colors of visible light correspond to different wavelengths. Wu\ elength A )) (X) Wavelength I lint I What is the Doppler effect? The frequency and wavelength of a wave are shifted if there is relative motion between the source and the observer of the waves. This is called the Doppler effect. It explains why the pitch of an ambulance siren drops as it races past you. Increased wavelength Reduced wavelength How will I use waves? Waves are literally everywhere. Communications systems from radios to cell phones to fiber optics use waves. Sonar and radar and medical ultrasound use waves. Music and musical instruments are all about waves. Waves are present in the oceans, the atmosphere, and the earth. This chapter and the next will allow you to understand and work with a wide variety of waves that you may meet in your career.

3 ?kaii oar Wedm V 7cF1-5 \Ir 5 17 t at 4-

4 The following is a snapshot at t=0 for a transverse wave traveling to the right with velocity m/s. Which of the following equations is correct for this wave? t) = sin[(1 x sin[( N 7C 79x ( )t V-3V. j,6,t y(x, = sink7c)x (ic)ti 5. None of the above. ALA V V; T meters f-_ kfrrk C.) = 1/4_ The following is a history at x= 0 meter of a transverse wave traveling to the left with velocity m/s. Which of the following equations is correct for this wave? 1. y(x,t) = sinhx+(71t1. y(x,t)= sin[ 5 x +(71)t 3. y(x,t) = sin[ (i1)x+ 5 t /0\ 4. y(x,t)= sinkic)x + (n)t] 5. None of the above.

5 A transverse wave is traveling to the right with velocity m/s and wave length 4m. What will the wave (shown on the right, at t = 0 sec.) look like at t =1.5 seconds? eter. AA TAiv meter... A transverse wave is traveling to the right with velocity m/s and wave length 4m. The following graph describes how the particle at x=3m vibrates. Draw a snap shot of the wave at t=1 second. y meter t=5) = 6 sec

6 A transverse wave is traveling to left with velocity m/s and wave length 4m. The following is a snap shot at t=0 seconds. Which of the following graphs best describes the vibration at x = m? y meter meter I y Two strings with different unit mass are tied in the center and attached with a tension of 1000N to two walls, as shown. What is the ratio of the wave's speed in the two strings? The wave speed in a wire is r = Ip 1 --C? I.A=50 g/m 1[1=18 g/m 1. vi/ v=9/5 vi/ v=3/5 3. vi/ v=5/3 4. vi/ v=5/9 5. vi/ v=1 V1,K ( T,t),

7 Two strings with different unit mass are tied in the center and attached with a tension of 1000N to two walls, as shown. What is the ratio of the wave's frequencies in the two strings? 1 I vt=50 g/m 11=18 g/m I 1. f11 f=915. f11 f=3/5 3. fi/ f=5/3 4. f11 f= f11 f=1 Two strings with different unit mass are tied together as shown. What will the waves look like in the two strings? Ignore reflections that might I occur at the knot. 1 1,1=50 g/m p=18 g/m A. i