The main-sequence turnoff of a star cluster tell us the cluster's
A.) Age.
B.) Mass.
C.) Distance.
D.) Composition.
E.) Size.
Ans: A.) Age.
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A toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed using 1000 J of work, is
A) 20 W. B) 50 W. C) 100 W. D) 1000 W. E) 20,000 W.
Type II supernovae and star forming regions are related to one another because:
A) they both contain ionized hydrogen. B) they both involve high mass ionizing stars. C) the shock waves of a supernova can trigger star formation. D) as a result of both processes, lighter elements are transformed into heavier elements. E) All of the above.
If there are other civilizations at present in the Milky Way Galaxy, which statement is almost undoubtedly true?
A) They are far more technologically advanced than we are. B) They are anatomically much like us, with two arms, two legs, two eyes, and two ears. C) They have social structures that are completely different from our own; for example, different types of "family" units, and so on. D) For fun, they enjoy "buzzing" to Earth and temporarily abducting people, showing a clear preference for people located in less-developed rural areas.
How far above the horizon is the Moon when its image reflected in calm water is completely polarized?
A) 36.9° B) 43.2° C) 46.8° D) 53.1° E) 57.5°