Ch13-Ans.Waves Motion.doc

I-Ch.13 Waves Motion , I-Ex. P.348: 10, 11, 13, 15 II-Ex. P.349: 21, 22 , 23, 26, 10. The wave on a string shown in Fig. 13-34 is moving to the right with a speed of 1.80m/s. (a) Draw the shape of the string 1.00 s later and indicate which parts of the string are moving up and which down at that instant, (b) Estimate the vertical speed of point A on the string at the instant shown in the figure.11. (II) S and P waves from an earthquake travel at different speeds and this difference helps in the determination of the earthquake epicenter (where the disturbance took place), (a) Assuming typical speeds of 9.0km/s and 5.5km/s for P and S waves, respectively, how far away did the earthquake occur if a particular seismic station detects the arrival of these two types of waves exactly 94 s apart? (b) Is one seismic station sufficient to determine the position of the focus? Explain.13. (I) Compare (a) the intensities and (b) the amplitudes of an earthquake P wave as it passes two points 10 km and 20 km from the source.15. (II) Show that if damping is ignored the amplitude DM of circular water waves decreases as the square root of the distance r from the source: II-Ex. P.349: 21, 22 , 23, 26, 21. (II) Consider a point on the string of Example 13-3 that is 1.00 m from the left-hand end. Determine (a) the maximum velocity of this point, and (b) its maximum acceleration, (c) What is its velocity and acceleration at t = 2.0 s?22. (II) Show, for a sinusoidal transverse wave traveling on a string, that the slope of the string at any point x is equal to the ratio of the transverse speed of the particle to the speed of the wave at that point.23. (II) A transverse wave pulse travels to the right along a string with a speed = 2.0 m/s. At t = 0 the shape of the pulse is given by the function D = 0.45cos(3.0x + 1.2). (a) Plot D versus x at t= 0. (b) Determine a formula for the wave pulse at any time t assuming there are no frictional losses, (c) Plot D(x, t) versus x at t = 1.0 s. (d) Repeat parts (b) and (c) assuming the pulse is traveling to the left.III-Ch.13 Waves Motion , III-Ex. P.350: 34, 35, 47, 51*, 34. (I) The two pulses shown in Fig. 13-36 are moving toward each other.(a) Sketch the shape of the string at the moment they directly overlap. (b) Sketch the shape of the string a few moments later, (c) In Fig. 13-23a, at the moment the pulses pass each other, the string is straight. What has happened to the energy at this moment?35. (II) Suppose two linear waves of equal amplitude and frequency have a phase difference as they travel in the same medium. They can be represented by D1 = DM sin(kx -t ) , D2 = DM sin(kx -t + ) 51. (II) Plot the two waves given in Problem 50, and their sum, as a function of time from t = 0 to t = T (one period). Choose (a) x = 0 and (b) x = /4. Interpret your results.Ch.13 Waves Motion , 50, 68，69, 71, 73, 74,71 Figure 13-40 shows the wave shape of a sinusoidal wave traveling to the right at two instants of time. What is the mathematical representation of this wave? 74. For a spherical wave t