Which of the following best describes the meaning of declination and right ascension?
A) They are coordinates on the celestial sphere, with declination telling us the angular distance of an object from the celestial equator and right ascension telling us how far around the celestial sphere an object is located from the March equinox.
B) They are coordinates on the celestial sphere that are similar to the coordinates of altitude and direction on Earth.
C) They are used to describe the locations and distances of stars that we see in the night sky.
D) They are terms used by astronomers to describe how the sky changes with the seasons.
A) They are coordinates on the celestial sphere, with declination telling us the angular distance of an object from the celestial equator and right ascension telling us how far around the celestial sphere an object is located from the March equinox.
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Beam ACB has a sliding support at A and is supported at C by a pinned-end steel column with square cross section (E 5 200 GPa, b 5 40 mm) and height L 5 3.75 m. The column must resist a load Q at B with a factor of safety of 2.0 with respect to the critical load. The max-imum permissible value of Q is approximately:
(A) 10.5 kN
(B) 11.8 kN
(C) 13.2 kN
(D) 15.0 kN
What is the wave speed in a brass wire with a radius of 0.500 mm stretched with a tension of 125 N? The density of brass is 8.60 × 103 kg/m3
A) 0.121 m/s B) 136 m/s C) 100 m/s D) 500 m/s E) 68.8 m/s
If you point toward the zenith right now and then point there again 6 hours later, you will have pointed twice in the same direction relative to
a. your horizon. b. the Sun. c. the Moon. d. the fixed stars.
Two tanks of gas, one of hydrogen, H2, and one of helium, He, contain equal numbers of moles of gas. The gram-molecular mass of He is twice that of H2 . Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?
a. The total internal energy of the hydrogen is the same as that of the helium. b. The total internal energy of the hydrogen is 1.4 times that of the helium. c. The total internal energy of the helium is 1.4 times that of the hydrogen. d. The total internal energy of the hydrogen is 1.67 times that of the helium. e. The total internal energy of the helium is 1.67 times that of the hydrogen.