Which of the following observations confirms that Sgr A at the center of our galaxy is indeed a supermassive black hole?
A) measurements of radio emission from gas around Sgr A
B) measurements of occasional X-ray emission from Sgr A
C) measurements of the orbits of stars around Sgr A
D) measurements of trans-dimensional space warps in the vicinity of Sgr A
C
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The energy of a photon is related to
A) the energy given to the atom that emits it. B) the energy transition in de-excitation. C) its frequency. D) all of the above E) none of the above
"Super-Earths" may be habitable at distances much greater from their star than Earth
Indicate whether the statement is true or false
Magnetic confinement is used in controlled fusion experiments to control a plasma
a. True b. False Indicate whether the statement is true or false
While the gondola is rising at a speed of 5.0 m/s, a passenger in a balloon-supported gondola throws a small ball up at a speed of 2.0 m/s relative to his body. A person who measures the ball's velocity at the instant of release will find that the ball's velocity relative to the ground at that instant is
a. 2.0 m/s, up. b. 2.8 m/s, down. c. 3.0 m/s, up. d. 5.0 m/s, up. e. 7.0 m/s, up.