© 2010 Pearson Education, Inc. Slide Traveling Waves and Sound

© 2010 Pearson Education, Inc. Slide 15-3

© 2010 Pearson Education, Inc. Slide 15-4

© 2010 Pearson Education, Inc. Slide 15-5

© 2010 Pearson Education, Inc. Types of Waves A transverse wave A longitudinal wave Slide 15-12

© 2010 Pearson Education, Inc. Waves on Strings and in Air Slide 15-13

© 2010 Pearson Education, Inc. Snapshot Graphs Slide 15-14

© 2010 Pearson Education, Inc. Constructing a History Graph Slide 15-15

© 2010 Pearson Education, Inc. Checking Understanding The graph below shows a snapshot graph of a wave on a string that is moving to the right. A point on the string is noted. Which of the choices is the history graph for the subsequent motion of this point? Slide 15-16

© 2010 Pearson Education, Inc. Answer The graph below shows a snapshot graph of a wave on a string that is moving to the right. A point on the string is noted. Which of the choices is the history graph for the subsequent motion of this point? (b) Slide 15-17

© 2010 Pearson Education, Inc. The graph below shows a history graph of the motion of one point on a string as a wave moves by to the right. Which of the choices is the correct snapshot graph for the motion of the string? Checking Understanding Slide 15-18

© 2010 Pearson Education, Inc. Answer (d) The graph below shows a history graph of the motion of one point on a string as a wave moves by to the right. Which of the choices is the correct snapshot graph for the motion of the string? Slide 15-19

© 2010 Pearson Education, Inc. A wave travels back and forth on a guitar string; this is responsible for making the sound of the guitar, as we will see. As the temperature rises, the tension in a guitar string decreases. How does this change the speed of a wave on the string? How do you measure the temperature of a flame if the temperature is higher than a probe can handle? One possible solution is to use sound. A source emits a pulse of sound on one side of the flame, which is then measured by a microphone on the other side. A measurement of the time between the emission and the reception of the pulse allows a determination of the temperature. Explain how this technique works. Conceptual Example Problems Slide 15-20

© 2010 Pearson Education, Inc. A particular species of spider spins a web with silk threads of density 1300 kg/m 3 and diameter 3.0 µm. A typical tension in the radial threads of such a web is 7.0 mN. If a fly lands in this web, which will reach the spider first, the sound or the wave on the web silk? Example Problem Slide 15-21

© 2010 Pearson Education, Inc. Sinusoidal Waves Slide 15-22

© 2010 Pearson Education, Inc. Checking Understanding For this sinusoidal wave: 1.What is the amplitude? A.0.5 m B.1 m C.2 m D.4 m Slide 15-23

© 2010 Pearson Education, Inc. Answer For this sinusoidal wave: 1.What is the amplitude? A.0.5 m B.1 m C.2 m D.4 m Slide 15-24

© 2010 Pearson Education, Inc. Checking Understanding For this sinusoidal wave: 2.What is the wavelength? A.0.5 m B.1 m C.2 m D.4 m Slide 15-25

© 2010 Pearson Education, Inc. Answer For this sinusoidal wave: 2.What is the wavelength? A.0.5 m B.1 m C.2 m D.4 m Slide 15-26

© 2010 Pearson Education, Inc. Checking Understanding For this sinusoidal wave: 3.What is the frequency? A.50 Hz B.100 Hz C.200 Hz D.400 Hz Slide 15-27

© 2010 Pearson Education, Inc. Answer For this sinusoidal wave: 3.What is the frequency? A.50 Hz B.100 Hz C.200 Hz D.400 Hz Slide 15-28

© 2010 Pearson Education, Inc. The new generation of cordless phones use radio waves at a frequency of 5.8 GHz. What is the wavelength of these radio waves? A speaker emits a tone of a particular frequency. Suppose the air temperature increases. What happens to the wavelength of the sound? Example Problems Slide 15-29

© 2010 Pearson Education, Inc. The water in the open ocean is in constant motion, carrying long- wavelength waves moving at relatively high speeds. Under steady winds, the amplitude of these waves can get quite large. Suppose a boat is at rest in the open ocean. The wind has created a steady wave with wavelength 190 m traveling at 14 m/s. (In fact, the ocean will support a mix of waves, but for steady winds of knots, this is the most prevalent wavelength, and the correct speed for a wave of this wavelength in deep water.) The top of the crests of the waves is 2.0 m above the bottom of the troughs. (This wave height is quite typical for windy days in the Atlantic Ocean. The Southern Ocean, with its planet-circling stretch of open water, supports much larger waves—wave heights of 7 m are quite common.) What is the maximum vertical speed of the boat as it bobs up and down on the passing wave? What is the maximum vertical acceleration? Example Problem Slide 15-30

© 2010 Pearson Education, Inc. Let’s use the data from the previous problem again. Suppose the boat is sailing at 6.0 m/s in the same direction as the motion of the waves. At t  0 s the boat is at the bottom of a trough. How high above this lowest point will the boat be at t  10 s? Example Problem Slide 15-31

© 2010 Pearson Education, Inc. Sound and Light Waves The speed of sound varies with the medium. Light and other electromagnetic waves in vacuum and in air move at the same speed, 3.00 x 10 8 m/s. Slide 15-32