When astronomers first saw the spectrum of a quasar they did not recognize it because
a) the lines were so far shifted towards the red
b) its spectral signature was masked by the presence of the central supermassive black hole
c) the chemical elements present in a quasar were unfamiliar
d) the lines were so far shifted towards the blue
e) it was too faint to produce spectral lines of any sort
Ans: a) the lines were so far shifted towards the red
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a. time dilation. b. length contraction. c. the equivalence of mass and energy. d. the principle of relativity. e. none of the above.
Strings that have more mass on a musical instrument than others produce notes of
A) higher frequency. B) lower frequency. C) the same frequency.
Two 0.20-kg balls, moving at 4 m/s east, strike a wall. Ball A bounces backwards at the same speed. Ball B stops. Which statement correctly describes the change in momentum of the two balls?
A.
.B.
.C.
.D.
.E.
.The half angle of the conical shock wave produced by a supersonic aircraft is 60°. What is the Mach number of the aircraft?
A) 2.0 B) 0.87 C) 1.73 D) 1.15 E)