In the Drake equation (Number of Civilizations = NHP × flife × fciv × fnow), what do we mean by fnow?
A) the fraction of planets with civilizations at the present time (as opposed to only in the past or future)
B) the fraction of planets in the galaxy on which a civilization could theoretically develop right now
C) the fraction of civilizations in the universe that currently are sending messages to us
D) the fraction of all species ever to exist that we currently are aware of
A) the fraction of planets with civilizations at the present time (as opposed to only in the past or future)
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Complete the following sentence: "The moment of inertia of an object
1.depends on the rotational speed of the object." 2.will be greater for a larger-massed object than for a smaller-massed object." 3.is not a function of the object's mass." 4.is a function of the axis about which the object is spun."
Rocks solidified from molten material below ground are classified as ______________ igneous rocks
Fill in the blank(s) with correct word
Imagine a steel pipe that doesn't leak from the sides and is already filled with water. Water enters at a rate of 2 kg/s but leaves at a rate of 1 kg/s. Which of the following is true?
A. The water pressure inside the tube rises as water is added B. The water flow must be laminar C. The tube is narrower where the water enters than where it leaves D. It is not possible for this situation to occur
Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.50 s and reaches the level of the top of the pole after a total elapsed time of 4.10 s
What was the speed of the ball at as it passed the top of the flagpole? A) 6.40 m/s B) 16.2 m/s C) 17.6 m/s D) 29.0 m/s E) 33 m/s