Why do we think that active galaxies have small core regions?
A. They emit radio waves that larger objects cannot do.
B. We can measure their size on the sky, which means they are small and near.
C. They are very far away, and thus are younger and less expanded.
D. Their light varies rapidly, implying small radius.
Answer: D
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A. 3.0 kJ B. 3.7 kJ C. 4.1 kJ D. 5.6 kJ E. 7.9 kJ
A light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts.If two slide projectors are connected in series across the same 120-volt source, the current drawn from the source in amperes is
a. 3. b. 6. c. 9. d. 12. e. none of the above.
An elementary particle has a measurable size
a. True b. False Indicate whether the statement is true or false
A body is oscillating up and down at the end of a spring. Let's consider when the body is at the top of its up and down motion. The net force on the body
a. is zero c. points up b. has its largest magnitude d. points down