What is the best evidence for a supermassive black hole in the center of the Milky Way Galaxy?
A) amazing filaments of radio emission swirling around the center of the galaxy
B) the motions of stars around a mysterious dark object
C) The existence of the Milky Way itself: The mass of the black hole is essential to gravitationally bind the galaxy together, so it doesn't fly apart.
D) the gigantic bursts of X-ray energy from a mysterious dark object
B
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How do human-built nuclear power plants on Earth generate energy?
A) chemical reactions B) nuclear fusion C) nuclear fission D) converting kinetic energy into electricity E) converting gravitational potential energy into electricity
The gap between electrodes in a spark plug is 0.06 cm. In order to produce an electric spark in a gasoline-air mixture, the electric field must reach a value of 3 × 106 V/m. What minimum voltage must be supplied by the ignition circuit when starting the car?
What will be an ideal response?
In the fusion of low-mass nuclei to make heavier nuclei
A) thermal energy is produced. B) nuclear energy is converted to other forms. C) the final nucleus has a smaller rest-mass than the total rest-mass of the original nuclei. D) All of the above.
Parallel light rays from a distant object strike the surface of a concave mirror. After reflecting from the mirror's surface, the rays will converge at
a. the mirror's focal point. b. a point beyond the mirror's focal point. c. a point nearer than the mirror's focal point. d. none of the above.