Explain how gas in a protostellar disk spirals onto the central star
What will be an ideal response?
Gas in a protostellar disk will orbit like planets, with the innermost particles moving faster than outer ones. This causes friction and therefore heating of the gas which therefore produces light (thermal radiation). Energy must be conserved so the gas loses gravitational potential energy and moves closer to the star. Because the gas is still in orbit, its overall motion is that of a spiral.
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An old 78 rpm record rotates through an angle of 320° as it slows down uniformly from 78.0 rpm to 22.8 rpm. What is the magnitude of the angular acceleration of the record?
A) 2.34 rad/s2 B) 5.46 rad/s2 C) 6.50 rad/s2 D) 8.35 rad/s2 E) 10.9 rad/s2
A 2.0-?F capacitor and a 4.0-?F capacitor are connected in series across an 8.0-V potential source. What is the charge on the 2.0-?F capacitor?
A) 2.0 ?C B) 11 ?C C) 4.0 ?C D) 25 ?C E) 12 ?C
The Copernican (heliocentric) model explained things better than the Ptolemaic (geocentric) model, except:
a. it did not explain the relative positions of stars as seen from Earth at different times of year. b. it did not explain why Mercury is always near the Sun. c. it was conceptually more complex than the Ptolemaic model. d. it did not explain planetary motion clearly. e. it required a great deal more mathematical calculation.
Water movement in a wave in the surf zone is characterized by
A) steepened wave height and longer wavelength. B) steepened wave height and shorter wavelength. C) a surfable wave crest and increased wavelength. D) shallow water depth and a steepened long wavelength.