Earthquakes essentially sound waves in Earths crust are an interesting example

# Earthquakes essentially sound waves in earths crust

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Earthquakes, essentially sound waves in Earth’s crust, are an interesting example of how the speed of sound depends on the rigidity of the medium. Earthquakes have both longitudinal and transverse components, and these travel at different speeds. The bulk modulus of granite is greater than its shear modulus. For that reason, the speed of longitudinal or pressure waves (P-waves) in earthquakes in granite is significantly higher than the speed of transverse or shear waves (S-waves). Both components of earthquakes travel slower in less rigid material, such as sediments. P-waves have speeds of 4 to 7 km/s, and S-waves correspondingly range in speed from 2 to 5 km/s, both being faster in more rigid material. The P-wave gets progressively farther ahead of the S-wave as they travel through Earth’s crust. The time between the P- and S-waves is routinely used to determine the distance to their source, the epicenter of the earthquake.
The speed of sound is affected by temperature in a given medium. For air at sea level, the speed of sound is given by where is the Boltzmann constant ( ) and is the mass of each (identical) particle in the gas. So, it is reasonable that the speed of sound in air and other gases should depend on the square root of temperature. 2. EXPERIMENTAL PROCEDURE: With the function generator, oscilloscope, amplifier, microphone, speaker, and tube all setup we were ready to analyze the standing sound waves. We first got the temperature of the room for later experimental standard. We set the tube at a certain length of 70 cm and inserted the microphone to position it in front of the piston. Connected the function generator to

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• Summer '20
• Wavelength, Standing wave, 5 km, 7 km

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