All of the following are true. Which of these gives evidence that quasars were more common when the universe was young than they are today?
A) They are more common at very great distances.
B) They are very bright.
C) They are active galactic nuclei.
D) We don't see them in every galaxy.
A) They are more common at very great distances.
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In what way do observations of binary star systems support the special theory of relativity?
A) The fact that the stars appear distinct supports the idea that the speed of light is unaffected by the motion of the stars. B) Stars in binary systems often orbit at speeds close to the speed of light, allowing us to check whether time dilation really occurs. C) Stars in binary systems are moving, so we can compare their moving masses to their rest masses. D) Binary systems have two stars, and therefore give us twice the opportunity to test the theory than single star systems.
Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?
A) the strength of protostellar winds B) the existence of protostellar jets C) the formation of a protostellar disk D) the onset of core hydrogen fusion
In the case of light waves, the thing doing the "waving" is
A) charged particles throughout the region between source and receiver. B) a gravitational field. C) the ether. D) an electromagnetic field. E) the air.
A certain car can accelerate from 0 to 100 km/hr in 6.0 seconds. What is the average acceleration of that car in m/s2?
What will be an ideal response?