Among spiral galaxies, an "SBa" has
A: no bar, tight smooth spiral arms, and a small bulge.
B: a bar, tight smooth spiral arms, and a large bulge.
C: a bar, very loose smooth spiral arms, and a moderate-sized bulge.
D: no bar, loose spiral arms, and almost no bulge.
E: a bar, jagged spiral arms, and a small bulge.
Ans: B: a bar, tight smooth spiral arms, and a large bulge.
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What kinds of objects are found in the Milky Way disk?
A. Blue stars B. Some red stars C. Open clusters D. Gas and dust E. All of the above
A series circuit consists of three identical lamps connected to a battery as shown in Figure OQ28.15. The switch S, originally open, is closed. What happens to the current in the battery?
Series Resonance: What size capacitor should be placed in series with a 30-? resistor and a 40-mH inductive coil if the resonant frequency of the circuit is to be 1.0 kHz?
A. 2.0 µF B. 0.63 µF C. 3.3 µF D. 6.0 µF E. 4.5 µF
Captain Ray, on the Galactic Explorer, sets off bright signal lights at the two ends of his spaceship so that they are seen as flashing simultaneously by General Kay, who is watch the ship go by. General Kay concludes that she was next to the midpoint of the ship at the instant when the lights flashed in her reference frame. This can only happen if Captain Ray, at the center of the Galactic
Explorer, a. sees the lights flash simultaneously in his coordinate system. b. sees the bow (front) light flash before the aft (rear) light. c. sees the aft (rear) light flash before the bow(front light. d. can calculate that the light flashes reach General Kay so that the flash from the bow light reaches her before the flash from the aft light. e. can calculate that the light flashes reach General Kay so that the flash from the aft light reaches her before the flash from the bow light.