Which of the following is a property of Seyfert galaxies?
A. Their nuclei have abnormally low luminosities.
B. The radiation from their cores fluctuates rapidly.
C. Most are elliptical galaxies.
D. They contain no gas clouds.
Answer: B
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Vision Problems: A nearsighted man wears contact lenses of -3.00 diopters. With these lenses, his corrected near point is 25.0 cm. What is his uncorrected near point?
Fill in the blank(s) with the appropriate word(s).
A juggler throws two balls to the same height so that one is at the halfway point going up when the other is at the halfway point coming down. At that point:
A. Their velocities and accelerations are equal. B. Their velocities are equal but their accelerations are equal and opposite. C. Their accelerations are equal but their velocities are equal and opposite. D. Their velocities and accelerations are both equal and opposite. E. Their velocities are equal to their accelerations.
What kind of waves are produced by the alternating current in standard electric power lines?
A) 60 Hz electromagnetic waves. B) 60 Hz electro-chemical waves. C) 100 MHz [mega-hertz] electromagnetic waves, in the FM radio region of the spectrum. D) Standard AC is simply a vibration of electrons that doesn't produce any kind of waves at all. E) 100 MHz sound waves.
A crate of weight w is being pushed across a horizontal surface by a force directed at an angle of 20° below the horizontal. What is the magnitude of the normal force on the crate?
a. It is less than w. b. It equals w. c. It is more than w. d. None of the above since the coefficient of kinetic friction is not given.