Earthquakes generate two sorts of waves in rock, shear or S waves which travel at about...

 

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Earthquakes generate two sorts of waves in rock, shear or S waves which travel at about 4.5 km/s and pressure or P waves traveling at about 8 km/s. (1) After one such quake, a seismograph station picks up the S wave 3.0 minutes after the P wave. How far away was the source, or epicenter, of the earthquake? [5 points] (2) When a quake is.detected, a steady 250 Hz alarm sounds in the hallway of a facility to alert the person on watch. The alarm is also sent to the cell phones of the staff on duty which emit the same 250 Hz tone. One of the staff responding to the alert runs down the hall, approaching the hallway speaker. She notices a 2 Hz variation in the loudness of the 250 Hz tone as she runs with her phone. What frequency is she hearing from the speaker? From your answer, how fast was she running, if the speed of sound is 344 m/s? A wave traveling through granite comes to a boundary with sandstone. The effective bulk modulus and density for each of these rocks is given in the table below. If you look up how to do this, I have already adjusted the bulk modulus using the shear modulus. Bulk modulus: Density kg/m3 GPa Granite 92 2660 Sandstone 15 2323 3) Calculate the wave speed for P waves in granite and in sandstone. 4) If the wave in the granite hits the boundary with the sandstone at an angle of 90° (head-on, no angle to worry about), describe the reflected and transmitted wave amplitudes (relative size, flipped or not). (No math here.) 5) Derive the transmission and reflection coefficients (the ratios of the reflected and transmitted amplitudes to the incident amplitude) and calculate their values. Omit any possible phase shifts here. It is simplest to set the boundary as x = 0 and use cosine functions for each of the 3 waves. Earthquakes generate two sorts of waves in rock, shear or S waves which travel at about 4.5 km/s and pressure or P waves traveling at about 8 km/s. (1) After one such quake, a seismograph station picks up the S wave 3.0 minutes after the P wave. How far away was the source, or epicenter, of the earthquake? [5 points] (2) When a quake is.detected, a steady 250 Hz alarm sounds in the hallway of a facility to alert the person on watch. The alarm is also sent to the cell phones of the staff on duty which emit the same 250 Hz tone. One of the staff responding to the alert runs down the hall, approaching the hallway speaker. She notices a 2 Hz variation in the loudness of the 250 Hz tone as she runs with her phone. What frequency is she hearing from the speaker? From your answer, how fast was she running, if the speed of sound is 344 m/s? A wave traveling through granite comes to a boundary with sandstone. The effective bulk modulus and density for each of these rocks is given in the table below. If you look up how to do this, I have already adjusted the bulk modulus using the shear modulus. Bulk modulus: Density kg/m3 GPa Granite 92 2660 Sandstone 15 2323 3) Calculate the wave speed for P waves in granite and in sandstone. 4) If the wave in the granite hits the boundary with the sandstone at an angle of 90° (head-on, no angle to worry about), describe the reflected and transmitted wave amplitudes (relative size, flipped or not). (No math here.) 5) Derive the transmission and reflection coefficients (the ratios of the reflected and transmitted amplitudes to the incident amplitude) and calculate their values. Omit any possible phase shifts here. It is simplest to set the boundary as x = 0 and use cosine functions for each of the 3 waves.