Which of the following is true of Seyfert galaxies?
A) They have inactive nuclei.
B) They mostly contain dying stars.
C) The spectra of their nuclei contain broad emission lines of highly ionized atoms.
D) The velocities of gas clouds at their centers are much less than velocities at the center of normal galaxies.
C
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A steel lift column in a service station is 4.0 m long and 0.20 m in diameter. Young's modulus for steel is 20 × 1010 N/m2. By how much does the column shrink when a 5000-kg truck is on it?
A) 4.7 × 10-7 m B) 8.0 × 10-7 m C) 3.2 × 10-6 m D) 7.8 × 10-6 m E) 3.1 × 10-5 m
RMS and Peak Quantities: The current through a 50-? resistor is I = (0.80 A) sin(240t), where t is measured in seconds. How much power on average is dissipated in the resistor?
A. 16 W B. 32 W C. 45 W D. 64 W
I stretch a rubber band and "plunk" it to make it vibrate in its fundamental frequency. I then stretch it to twice its length and make it vibrate in the fundamental frequency once again. This rubber band is made so that doubling its length doubles the tension and reduces the mass per unit length by a factor of 2 . The new frequency will be related to the old by a factor of:
a. 4.0. c. 1.4. b. 2.0. d. 1.0.
Hydrogen atoms in palladium form a(n) _____________solid solution.
Fill in the blank(s) with the appropriate word(s).