Which of the following is a main sequence star hotter than the Sun? (Note: the Sun is a G2V star.)
A. O2II
B. G1II
C. K2V
D. G1V
E. G2III
Answer: D
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What observational evidence supports the galactic fountain model, which describes how gas cycles between the disk of the galaxy and regions high above the disk?
A) We see hot gas high above the region of the disk near our solar system, along with cool gas that appears to be raining down from the halo. B) We have discovered a jet of ionized gas shooting out of the bulge of our galaxy. C) We have discovered that the entire galactic disk is being uniformly "rained on" by cool gas coming from the halo. D) We have observed a lot of water molecules in the interstellar medium.
At present, what is the primary way that the search for extraterrestrial intelligence (SETI) is carried out?
A) by using radio telescopes to search for signals from extraterrestrial civilizations B) by analyzing high-resolution images of nearby stars in search of evidence for structures that could not have developed naturally C) by searching for planets around distant stars D) by using x-ray telescopes to search for exhaust from interstellar spacecraft E) by seeking access to the secret records and alien corpses kept at the military's Area 51 in Nevada
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. How far below the level from which it was thrown is the rock 2 seconds later?
A) 5 m B) 10 m C) 15 m D) 20 m
In a capacitor in an AC circuit, the voltage:
a. lags the current by 90°. b. may lead or lag the current depending on the frequency. c. leads the current by 90°. d. is in phase with 70.7% of the current.