Briefly summarize current knowledge about the term Np in the equation Number of Civilizations = Np × flife × fcivilization × fnow
What will be an ideal response?
We have evidence now for more than a dozen planets around other stars, and evidence for protoplanetary disks around many more stars. Although we cannot yet give a precise value to Np, it now seems likely that it is quite large—perhaps as large as the number of stars in the Milky Way Galaxy.
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On a Hertzsprung-Russell diagram, where would you find stars that have the largest radii?
A) upper right B) lower right C) upper left D) lower left
The heating coil of a hot water heater has a resistance of 20 ohms and operates at 210 V. If electrical energy costs 5.5 cents per kW-hr, what does it cost to raise the 200 kg of water in the tank from 15°C to 80°C? (The specific heat of water is 4 186 J/kg°C)
In a GUT (Grand Unified Theory), what is "unified"?
A. matter and energy B. subatomic particles C. all of space D. galaxies E. the fundamental forces
Light enters air from water. The angle of refraction will be
A) greater than the angle of incidence. B) equal to the angle of incidence. C) less than the angle of incidence.