What theory do astronomers think explains the activity in galaxies?
A. a chain reaction of supernovas
B. a cosmic worm hole
C. the explosion of a supermassive star
D. a supermassive black hole
E. All of these choices are correct.
Answer: D
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Interplanetary radio station KLGM broadcasts at a frequency of 101 MHz. If you are in a high speed rocket heading straight toward the station, where should you tune your radio to get the best reception of station KLGM? (Hint: Consider the Doppler effect and remember the relationship between wavelength and frequency.)
a) exactly 101 megahertz b) less than 101 megahertz c) greater than 101 megahertz
In a two-body collision, if the momentum of the system is conserved, then which of the following best describes the kinetic energy after the collision?
a. must be less b. must also be conserved c. may also be conserved d. is doubled in value
A diatomic molecule consists of two point masses, m1 and m2, separated by a distance r. Find the moment of inertia through the center of mass about an axis perpendicular to the molecular axis
a. m1m2r2/(m1 + m2) b. [(m1m2/m1) + m2]r2 c. (m1 + m2)/m1m2r2 d. (m1 + m1)r2 /m1m2 e. m1m2r2/m1
As the speed of an object increases, its wavelength
a. remains unchanged. b. decreases. c. increases. d. is zero.