Interferometry
a. is used to improve the resolving power.
b. decreases the chromatic aberration of a telescope.
c. works only for large X-ray and ultraviolet telescopes.
d. requires that radio telescopes be within a few hundred feet of each other.
e. is none of the above.
a
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The wobble of Earth's rotational axis resulting in a change in location of the north celestial pole is called ________.
A. the Coriolis effect B. differentiation C. revolution D. deflection E. precession
Whether or not a planet like Mercury can hold a particular gas in its atmosphere depends on that planet's
a. ice cap. b. craters. c. escape velocity. d. its distance from the Sun as manifested in the temperature of the atmosphere. e. escape velocity and its distance from the Sun as manifested in the temperature of the atmosphere.
Would a nitrogen atom in Venus's atmosphere, whose temperature is 740 K, eventually es-cape into outer space? Note that a nitrogen atom has a mass that is 14 times that of a hydro-gen atom. Recall that atoms eventually will escape if their average velocity is greater than 1/6 times the escape velocity of the planet. The escape velocity of Venus is 10 km/s. For comparison, a hydrogen atom has an average velocity of 2.5 km/s at a temperature of 300 K.
a. The average velocity of nitrogen atoms is 0.4 km/s, and nitrogen does not escape. b. The average velocity of nitrogen atoms is 1.0 km/s, and nitrogen does not escape. c. The average velocity of nitrogen atoms is 1.0 km/s, and nitrogen escapes. d. The average velocity of nitrogen atoms is 4.5 km/s, and nitrogen does not escape. e. The average velocity of nitrogen atoms is 4.5 km/s, and nitrogen escapes.
The equation was recommended by H. Hausen (Zeitschr. Ver. Deut. Ing., Belherft No. 4, 1943) for forced-convection heat transfer in fully developed laminar flow through tubes. Compare the values of the Nusselt number predicted by Hausen’s equation for Re = 1000, Pr = 1, and L/D = 2, 10 and 100, respectively, with those obtained from two other appropriate equations or graphs in the text.
GIVEN
• Fully developed laminar flow through a tube
• The Nusselt number correlation shown above
• Reynolds number (Re) = 1000
• Prandtl number (Pr) = 1
• Length divided by diameter (L/D) = 2, 10, or 100
FIND
• The Nusselt number (Nu) from the above correlation and two others from the text
ASSUMPTIONS
• ?b / ?s ? 1.0
• Constant wall temperature
SKETCH
