The idea that other civilizations are waiting for us to reach a certain technological level before revealing themselves to us is referred to as the
A) conspiracy hypothesis
B) UFO hypothesis
C) sentinel hypothesis
D) zoo hypothesis
C
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Which photo shows what we call a gibbous moon? (Note: Assume these photos were taken in the Northern Hemisphere.)
A) 1 B) 2 C) 3 D) 4
According to our theory of solar system formation, why do we find some exceptions to the general rules and patterns of the planets?
A) Our theory is not quite correct because it cannot explain these exceptions. B) Most of the exceptions are the result of giant impacts or close gravitational encounters. C) The exceptions probably represent objects that formed recently, rather than early in the history of the solar system. D) The exceptions probably represent objects that were captured by our solar system from interstellar space. E) The exceptions are probably the result of the Sun passing very close to another star billions of years ago.
According to general relativity, what is a black hole?
A) an object that cannot be seen B) a place where light travels slower than the normal speed of light C) a place where the strength of gravity is infinite D) a hole in the observable universe
A large, metallic, spherical shell has no net charge. It is supported on an insulating stand and has a small hole at the top. A small tack with charge Q is lowered on a silk thread through the hole into the interior of the shell. What is the charge on the outer surface of the shell now?
1.Q 2.Q/2 3.0 4.-Q/2 5.-Q