In the Drake equation, Nc = N* × fp × nHZ × fL × fI × fs, the factor Nc is:
A) the number of planets in a solar system.
B) the average number of stars that have planets.
C) the average number of planets in each solar system suitably placed in the habitable zone.
D) the number of technological civilizations in the Milky Way Galaxy with which you might communicate.
D
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A 1200-kg cannon suddenly fires 100kg cannonball at 35m/sWhat is the recoil speed of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally
A) 35 m/s B) 3.5 m/s C) 3.2 m/s D) 2.9 m/s
How small a time interval is needed for a good calculation of instantaneous speed?
a. Instantaneous speed is calculated for a single instant. b. Three days is small enough. c. Use the longest interval of travel to avoid numerical error. d. An interval short enough so that the answer won't change very much if you use a shorter one. e. A single second is short enough.
An unconformity can be interpreted as
A) an occurrence of radioactive decay. B) repeated intrusions of igneous rock. C) a buried surface of erosion. D) the result of repeated volcanic action.
Which of these is NOT a function of a calendar?
A. Be useful to a large number of people for communication regarding dates. B. Use natural time intervals such as those defined by the Moon. C. Be able to accurately predict when an asteroid will strike the Earth. D. Keeps track of time over long periods.