Besides Earth, which of the terrestrial planets and/or satellites of terrestrial planets show(s) evidence for the possible existence of liquid water flowing on its surface in the past?
a. Venus
b. the Moon
c. Phobos
d. Mars
e. None of the terrestrial planets or satellites show such evidence.
d
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In partially stabilized zirconia (ZrO2), the addition of materials such as MgO or CaO lowers the temperature of the _________transformation of the tetragonal to the monoclinic phase.
Fill in the blank(s) with the appropriate word(s).
A massive star can fuse more and more massive nuclei, but this process is limited by the fact that, at some point, an element that is produced ____
a. becomes completely degenerate in the core, changing the pressure-temperature relationship b. cannot produce energy through fusion c. will only fuse in the presence of even more massive nuclei d. is not found in nature e. decays radioactively before it can undergo fusion
Geological evidence points to a few very deep "snowball" phases in Earth's history, in which the oceans would have been mostly frozen. How did Earth recover from a snowball phase?
A) The increased ice coverage on Earth's surface absorbed more sunlight than water and rocks, thus gradually heating Earth until the ice melted. B) Life vanished, leading to an increase in CO2, and increased global warming, eventually melting the ice. C) Volcanoes continued to inject CO2 into Earth's atmosphere, increasing the greenhouse effect to the point where ice melted. D) Plate tectonics gradually subducted all the ice below Earth's surface. E) As the Sun aged, it grew brighter and increased Earth's temperature, melting the ice.
The windings of a DC motor have a resistance of 6.0 ?. The motor operates on 120. V AC, and when running at full speed it generates a back emf of 105. V
(a) What is the starting current of the motor? (b) What current does the motor draw when operating at full speed?