Consider three galaxies, Alpha, Beta and Gamma. An observer in Beta sees the other two galaxies each moving away from him in opposite directions at speed 0.70c. At what speed would an observer in Alpha see the galaxy Beta moving?
A) 0.82c
B) 0.70c
C) 0.94c
D) 0.35c
E) 0.57c
B
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Double-lobed radio galaxies appear to be emitting jets of gas and radiation
Indicate whether the statement is true or false
Acrux has an MV = –4.2 and an mV = 0.81 . Therefore, Acrux is actually brighter than we perceive it to be
a. True b. False Indicate whether the statement is true or false
Two beams of coherent light are shining on the same piece of white paper. With respect to the crests and troughs of such waves, darkness will occur on the paper where:
a. the crest from one wave overlaps with the crest from the other. b. the crest from one wave overlaps with the trough from the other. c. the troughs from both waves overlap. d. darkness cannot occur as the two waves are coherent.
The following set of redox reactions takes place when iron is dipped in a solution of copper ions
Fe ? Fe+2 + 2e- Cu+2 + 2e- ? Cu Which of the following describes what is happening on the surface of the iron? A) The copper starts to plate out on iron. B) The iron rusts in the water. C) The iron starts to plate out on the copper. D) The iron corrodes the copper. E) none of the above