According to current understanding, what is a quasar?
A) an active galactic nucleus that is particularly luminous
B) a large galaxy thought to be formed by the merger of several smaller galaxies, typically found in the center of a galaxy cluster
C) Any object with an extremely large redshift is called a quasar.
D) a galaxy with an unusually high rate of star formation
A) an active galactic nucleus that is particularly luminous
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A spaceship from another galaxy passes over the solar system directly above a radial line from the Sun to the Earth. (We measure that distance to be 1.5 × 1011 m.) On Earth, the spaceship is observed to be traveling at a speed of 0.80c, for which ? = 5/3. As measured on Earth it takes the spaceship 625 seconds to travel from the Sun to Earth. When a scientist in the spaceship measures the Earth-Sun distance and the time it takes her to travel that distance, she finds the results are, respectively
A. 9.0 × 1010 m; 375 s. B. 9.0 × 1010 m; 625 s. C. 1.5 × 1011 m; 625 s. D. 2.5 × 1011 m; 625 s. E. 2.5 × 1011 m; 1042 s.
Why is infrared much better than visible light in studying star formation?
What will be an ideal response?
Water, of density 1000 kg/m3, is flowing in a drainage channel of rectangular cross-section. The width of the channel is 15 m, the depth of the water is 8.0 m and the speed of the flow is 2.5 m/s. At what rate is water flowing in this channel?
A) 2.0 × 105 kg/s B) 2.0 × 103 kg/s C) 3.0 × 105 kg/s D) 3.0 × 103 kg/s E) 3.0 × 102 kg/s
A circuit consists of an AC audio amplifier, a resistor, and a speaker, all in series. The amplifier puts out an alternating voltage of 16.0 V (rms), the resistance of the resistor is 10.0 ?, and the speaker has a resistance of 11.9 ?. What is the time-averaged power delivered to the speaker?
a. 21.5 W b. 30.5 W c. 6.35 W d. 8.69 W