Posted on 09/22/2003 11:51:44 PM PDT by Aracelis
Only if "Her" name is Hillary....
Not to pick nits, but are earthquake waves really longitudinal/compression, rather than transverse?
This is where I stopped reading. The gender of the pronoun should be determined by the likelihood of an astronaut to be one or the other. Since more than 90% of astronauts (I'm guessing) have been male, using "her" in the sentence is just political correctness.
I knew a male english professor cum bureaucrat who would always do that, and make a big point of casualness when he did. He worked for a woman. He was also privately alleged by several women who worked under and around him to be a serial harasser to the point of being a borderline rapist.
There's a physics reason. Very few males are sufficiently shrill to do this.
Traditionally, the masculine is generic. "Mankind" refers to all humans, not just men ;)
Actually, there are several types of seismic waves:
P waves - Compressional waves, Primary waves, Longitudinal waves
These waves alternate compressions with dilations, and are directed in the direction of propagation (perpendicular to the wavefront). P-wave motion travels fastest in solid materials, and are the first-arriving energies on a seismogram (P-wave). P waves in liquid, gas, or air are pressure waves.
velocity = about 5 – 7 km/s in Earth’s crust; about 8 km/s in Earth’s mantle and core; about 1.5 km/s in water; 0.3 km/s in air
S waves - Shear, Secondary waves, Transverse waves
These waves oscillate in a transverse fashion perpendicular to the direction of propagation either in the vertical or horizontal plane. S-waves do not travel through fluids, air, water or molten rock. A liquid outer core has been inferred from their absence in seismic records. S-waves travel more slowly than P waves in solids, and therefore arrive after the P wave.
velocity = about 3 – 4 km/s in Earth’s crust; about 4.5 km/s in Earth’s mantle; about 2.5 - 3.0 km/s in Earth's solid inner core
L waves - Love waves, Surface waves, Long waves
L-waves display transverse horizontal motion, perpendicular to the direction of propagation and parallel to the Earth’s surface. Love waves are largest at the Earth's surface and decrease in amplitude with depth. Love waves are dispersive, with lower frequencies normally propagating at a higher velocity. Depth of penetration is also frequency-dependent, with lower frequencies penetrating to greater depths.
velocity = about 2.0 - 4.5 km/s depending upon the frequency of the propagating wave
R waves - Rayleigh waves, Surface waves, Long waves, Ground roll
R-waves move both in the direction of propagation and perpendicular to the vertical. Motion is generally elliptical. Rayleigh waves are dispersive, and amplitudes generally decrease with depth inside the Earth. Their appearance is similar to water waves.
velocity = about 2.0 - 4.5 km/s in the Earth depending upon frequency of the propagating wave
And also this kind of WAVE.
I cringe at the specter of gender-free language, wherein we will be forced to refer to that reknowned English soccer team as "Peoplechester United" and those round steel thingies in the sewer sytem as "personhole" covers.
Gyno-American Grammar is evil.
... I'm ... curious about the original article. Consider the introduction:"B-flat flying through space ... 57 octaves below the keys in the middle of a piano."
Wow, 57 octaves below B-flat, eh?
Assuming we are using A-440 Hz (and not some pre-Bach value), the B-flat below middle-C vibrates a medium only 233.0818808 times per second.
57 octaves below that is roughly 1.61733e-15 vibrations per second. This means that the period of the wave is the inverse of that number, or 6.18303e+14 seconds. But, ...
6.18303e+14 seconds
equals
1.71751e+11 hours
equals
7156282833 days
equals
19606259.51 years.Call me suspicious, but how exactly does one make a measurement of a physical process which occurs once every 19 million years? Is there something in the fossil record, perhaps scratchings on a rock thanks to an inquisitive T. Rex?
Granted, if the note in question is 57 octaves below the B-flat which is above middle C, then you only have to wait half that long.
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