Which of the following was the first strong evidence for an asteroid impact being the cause of the extinction of the dinosaurs 65 million years ago (as well as 75% of all species alive at the time)?
A) a worldwide layer rich in the element iridium that dates to that time
B) the discovery of asteroid fragments in dinosaur bones dating to that time
C) the fact that dinosaurs appear to have gone abruptly extinct at about that time
D) careful studies of lunar craters suggesting an unusually large number of impact at that time
A) a worldwide layer rich in the element iridium that dates to that time
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Compared to today, in the future, the Sun's habitable zone will be
A) wider and closer to the Sun B) narrower and closer to the Sun C) narrower and farther from the Sun D) wider and farther from the Sun
A phenomenon that occurs in the ionosphere is
a. the greenhouse effect. b. photosynthesis. c. Rayleigh scattering. d. auroras.
A Sense of Proportion: Arrange the following discoveries from earliest to most recent:
A step-up transformer has an input voltage of 110 V (rms). There are 100 turns on the primary and 1500 on the secondary. What is the output voltage?
a. 1 600 V (max) b. 1 650 V (rms) c. 3 260 V (max) d. 165 kV (rms) e. 7.3 V (rms)