We suspect that quasars are the active centers of galaxies because
a. "fuzz" around the central luminous regions produces spectra like a collection of normal stars..
b. a few quasars have large red shifts.
c. the central regions of some quasars fluctuate rapidly.
d. all of the above
e. none of the above
A
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Advantages of radio astronomy include
A) radio waves are not scattered or deflected by Earth's atmosphere. B) radio observations can be made even when the Sun is in the sky. C) radio observations can be made even when the sky is obscured by clouds. D) radio observations let astronomers study things that emit little visible light. E) all of the above.
A point on the rim of a 0.30-m radius rotating wheel has a tangential speed of 4.0 m/s. What is the tangential speed of a point 0.10 m from the center of the same wheel?
a. 1.0 m/s c. 2.7 m/s b. 1.3 m/s d. 8.0 m/s
During a solar eclipse, the Moon's phase must be
A) first quarter. B) third quarter. C) full. D) new.
Suppose David Ortiz hits a home run which travels 361. feet (110. m). Assuming it left the bat at 50.°, how fast was it hit?
What will be an ideal response?