In the Drake equation (Number of Civilizations = NHP × flife × fciv × fnow), we expect the term fciv to be small if ________
A) most of the civilizations that have ever existed are still out and about in the galaxy
B) primitive life is common but intelligent life is rare
C) most habitable planets never actually get life on them
D) most civilizations destroy themselves within just a few hundred years of arising
B
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Density: Substance A has a density of 3 g/cm3 and substance B has a density of 4 g/cm3. In order to obtain equal masses of these two substances, what must be the ratio of the volume of A to the volume of B?
A. 
= 
B. 
= 
C. 
= 
D. 
= 
E. 
= 
________ looked very bland in Voyager 2 photos in 1986, but as equinox approached in the 1990s, its disk showed belts, zones, and storms
Fill in the blank(s) with correct word
If you stand on a weighing scale and suddenly the atmosphere vanishes, taking buoyancy into account, the scale reading
A) increases. B) decreases. C) remains the same. D) quickly reduces to zero.
1.0 kg is at (-2.0, 2.0); 2.0 kg is at (2.0, -4.0); and 3.0 kg is at (2.0, 0.0)
(a) What is the x coordinate of the center of mass? (b) What is the y coordinate of the center of mass?