Why do we believe that starburst galaxies represent a temporary stage in galaxy evolution?
A) We observe starbursts to last only a few years at a time.
B) Such galaxies produce so much light that they would have consumed all their gas long ago if they had always been forming stars at this high rate.
C) We don't see any nearby starburst galaxies.
D) All starburst galaxies look like normal spiral galaxies, aside from the starbursts.
B
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Which statement about the rotations of the Moon and Mercury is FALSE?
A) Our Moon is in a 1:1 synch with the Earth, keeping the same side toward us. B) Mercury is in the 3:2 synch with the Sun, with the same side Sunward at perihelion. C) Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun. D) On Mercury, three days exactly equal two years. E) On the Moon, each "day" lasts about 15 Earth days of constant sunlight.
Event 2 occurs a time â^†t after event 1. If event 2 was caused by event 1, which of the following must be true?
A. The distance between event 1 and event 2 can be any amount. B. The distance between event 1 and event 2 is not more than c â^†t. C. There are frames of reference in which event 2 is before event 1. D. There are frames of reference in which event 1 is not related to event 2. E. All of these choices are false.
In 1989, Neptune was found to have a huge storm named the
A) South Tropical Disturbance. B) Great Red Spot. C) Great Dark Spot. D) Hellas Basin. E) Galileo Regio.
______________ principle explains why objects float or sink in a fluid
a. Newton's b. Pascal's c. Bernoulli's d. Archimedes'