Why do you see lightning before you hear the thunder? Would you see a rocket lift off from the moon before you heard it?
Young and Freedman 19-35:
Earthquakes produce both longitudinal seismic waves, called P waves, and transverse seismic waves, called S waves. At a depth of 1000 km below the earth’s surface, s waves travel at approximately 6400 m/s. a) What is the wavelength of an S wave with an oscillation period of 2.0 s? b) The Richter magnitude scale is used to measure the destructive strength of earthquakes. The Richter magnitude m is a pure number, defined as m=log(A/T ) + B, where a is the amplitude of the wave in micrometers as measured by a seismometer, T is the period of the earthquake oscillations in seconds, and B is an empirical factor that depends on the distance from the epicenter of the quake to the location of the seismometer. How is m affected is A increases? If T increases? Explain why the destructive strength of an earthquake should depend on A and T in this way. c) Calculate the Richter magnitude of the earthquake that causes the seismic wave in part9a) if a seismometer 10,000 km from the epicenter detects oscillations with A= 10 micrometers. At this distance, B=6.8. How does this compare to the Loma Prieta earthquake (which I happened to experience about 20 miles from the epicenter) which had Richter magnitude of 7.1. (Damage begins at m=5 and the largest earthquakes ever measured have m=8.5)
When a rock is thrown into a pond and the resulting ripples spread in ever-widening circles, the amplitude decreases with increasing distance from the center. Why?
Young and Freedman 20-11:
A stretched string vibrates with a frequency of 25.0 Hz in its fundamental mode when the supports to which the ends of the string are tied are 0.800 m apart. The amplitude at the antinode is 0.50 cm. The string has a mass of 0.0500 kg. a) What is the speed of propagation of a transverse wave in the string? b) Compute the tension in the string.
If you stretch a rubber band and pluck it, you hear a (somewhat) musical tone. How does the frequency of this tone change as your stretch the rubber band further? Explain this in terms of the wave phenomena you are studying.
Young and Freedman 20-23:
Figure 20-25 on page 643 of the text shows two rectangular wave pulses on a stretched string traveling toward each other. Each pulse is traveling with a speed of 1.00 mm/s and has the height and width shown in the figure. If the leading edges of the pulses are 8.00 mm apart at t=0, sketch the shape of the string at t= 4.00 s, 6.00 s, and 10.0 s.