An earthquake emits both P waves and S waves that travel at different speeds through the Earth. Suppose a P wave travels at 8000 m/s and an S wave at 4000 m/s. If P waves are received at a seismic station 20.0 s before an S wave arrives, how far is the station from the earthquake center?
a. 80 km
c. 240 km
b. 160 km
d. 320 km
B
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Weight and g: An astronaut goes out for a "space-walk" at a distance above the earth equal to the radius of the earth. What is her acceleration due to gravity at that point?
A. zero
B. g
C. g/2
D. g/4
E. g/
Neptune's large moon ________ is the only large satellite known in a retrograde orbit
Fill in the blank(s) with correct word
Which of the following best describes the current scientific view of possibilities of travel to distant parts of our galaxy (or universe) with such things as hyperspace, wormholes, or warp drive?
A) We do not know if travel in any of these ways is really possible, but they do not contradict any known laws of physics. B) There is no doubt that such travel is possible, though it remains well beyond our current technology. C) They sound like fun, but they are not possible because they allow faster-than-light travel. D) They seemed to be allowed by special relativity, but general relativity does not allow for them.
Which of the following describes what will happen to a light ray incident on an air-to-glass boundary at less than the critical angle?
a. total reflection b. total transmission c. partial reflection, partial transmission d. partial reflection, total transmission