How long do sunspots typically last? Choose the best answer
a. an hour b. a day
c. a week d. two weeks or a fortnight
d
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In the equation: Number of Civilizations = Np × flife × fcivilization × fnow what do we mean by fnow?
A) the fraction of planets with civilizations on which the civilizations exist now B) the fraction of time since the Big Bang represented by the present era C) the fraction of all species ever to exist that we currently are aware of D) the fraction of planets in the galaxy on which a civilization could theoretically develop now E) the fraction of civilizations in the universe that currently are sending messages to us
For electromagnetic radiation of intensity of
what is the rms value of the electric field?
a. 
b. 
c. 
d. 
e. 
One gram of water is heated from 0°C to 100°C at a constant pressure of 1 atm. Determine the approximate change in internal energy (in cal) of the water
a. 160 b. 130 c. 100 d. 180 e. 50
An object is attached to a vertical ideal massless spring and bobs up and down between the two extreme points A and B. When the kinetic energy of the object is a minimum, the object is located
A) 1/4 of the distance from A to B. B) midway between A and B. C) 1/ times the distance from A to B. D) 1/3 of the distance from A to B. E) at either A or B.