The ____ of a comet is a lump of fragile, porous material containing ices of water, carbon dioxide, and ammonia
a. nucleus
b. coma
c. dust tail
d. gas tail
e. chondrule
a
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As a wave-generating object moves through a medium, the waves ahead
A) bunch up. B) stretch out. C) neither of these
Emission nebula appear red because they are associated with cool red giant stars
Indicate whether the statement is true or false
A heavy rock and a light rock are dropped from the same height and experience no significant air resistance as they fall. Which of the following statements about these rocks are correct? (There could be more than one correct choice.)
A) Both rocks have the same kinetic energy when they reach the ground. B) Both rocks have the same speed when they reach the ground. C) The heavier rock reaches the ground before the lighter rock. D) Just as they were released, both rocks had the same amount of gravitational potential energy. E) When they reach the ground, the heavier rock has more kinetic energy than the lighter rock.
Which is more common: a star blows up as a supernova, or a star ejects a planetary nebula?
A) Planetary nebulas are more common. B) Supernovae are more common. C) They both occur in about equal numbers. D) It is impossible to say.