The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?
A) It is no longer discussed, because as part of its broad cover-up of UFOs, the United States government has classified all the material relating to this debate as Top Secret.
B) We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare.
C) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are rare.
D) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are common.
B
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Transformers: You need an ideal transformer to reduce a voltage of 150 V in the primary circuit to 25 V in the secondary circuit. The primary circuit has 130 windings and the secondary circuit is completed through a 55-? resistor. How many windings should the secondary circuit contain?
Fill in the blank(s) with the appropriate word(s).
Dielectrics: A dielectric material such as paper is inserted between the plates of a capacitor as the capacitor holds a fixed charge on its plates. What happens to the electric field between the plates as the dielectric is inserted?
A. There is no change in the field. B. The field becomes stronger. C. The field becomes weaker. D. The field reduces to zero.
A split highway has a number of lanes for traffic. For traffic going in one direction, the radius for the inside of the curve is half the radius for the outside. One car, car A, travels on the inside while another car of equal mass, car B, travels at equal speed on the outside of the curve. Which statement about resultant forces on the cars is correct?
A. The force on A is half the force on B. B. The force on B is half the force on A. C. The force on A is four times the force on B. D. The force on B is four times the force on A. E. There is no net resultant force on either as long as they stay on the road while turning.
An object is dropped from a bridge. A second object is thrown downwards 1.00 s later. They both reach the water 20.0 m below at the same instant. What was the initial speed of the second object?
A) 4.91 m/s B) 14.6 m/s C) 9.90 m/s D) 19.6 m/s E) 21.3 m/s