Most active galactic nuclei are at large distances from us; relatively few nearby galaxies harbor active galactic nuclei. What does this imply?
A) Massive black holes existed only when the universe was young and no longer exist today.
B) Active galactic nuclei tend to become less active as they age.
C) The jets seen in many active galactic nuclei must cause them to move far away from us.
D) Active galactic nuclei can form only at large distances from the Milky Way.
B
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Doppler shifted hydrogen absorption lines are seen in the spectrum of a star. The hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm. The star is moving at which fraction of the speed of light?
A) about 0.000003 (3 × 10?6 ) B) about 0.0003 (3 ×10?4 ) C) about 0.2 D) about 0.03 (3 × 10?2 )
A circuit consists of a 11.4-mH coil, a 19-? resistor, a 5.0-? resistor, a 10-V battery and a switch, all in series. What is the time constant of this circuit?
a. 2.1E–3 s b. 4.8E–3 s c. 2.9E–3 s d. 4.8E–4 s e. 4.2E–1 s
A 3.0-kg object moving in the positive x direction has a one-dimensional elastic collision with a 5.0-kg object initially at rest. After the collision the 5.0-kg object has a velocity of 6.0 m/s in the positive x direction. What was the initial speed of the 3.0 kg object?
A. 6.0 m/s B. 7.0 m/s C. 4.5 m/s D. 8.0 m/s E. 5.5 m/s
The glass in a window is 35 inches wide and 20 inches tall, and standard atmospheric pressure is 14.7 pounds per square inch. What net force would result on the glass if the air pressure outside the house were 1% lower than the air pressure inside?
A. 10300 pounds outward B. 103 pounds inward C. There would be no net force D. 103 pounds outward E. 10300 pounds inward