Although it hasn't been observed (yet), why do astronomers think that the Milky Way is embedded in a halo of dark matter?
A. Due to its large size, the light from stars on the other side of the Milky Way has not reached us yet.
B. Stars in the outer regions of the Galaxy are orbiting faster than expected.
C. Astronomers have detected neutrinos from unseen sources.
D. Theory predicts that there should be more black holes than we've so far detected.
Answer: B
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The velocity of an airplane with respect to the ground is 
m/s at an angle of 30.0 degrees NORTH of EAST. The velocity of the airplane with respect to the air is 
m/s at an angle of 60.0 degrees NORTH of EAST. What is the velocity of the air with respect to the ground?
A. 112 m/s at 50.0 degrees NORTH of EAST B. 102 m/s at 17 degrees SOUTH of EAST C. 134 m/s at 49 degrees SOUTH of EAST D. 134 m/s at 17 degrees NORTH of EAST E. 102 m/s at 65 degrees NORTH of EAST
Blow on your hand with your mouth open. Then do the same with your lips puckered and you'll find
A) a difference in temperatures. B) the breath from puckered lips is cooler. C) both of these D) neither of these
Seafloor spreading on the Earth is the process by which
A) volcanic material flows from the deep interior to produce volcanic islands B) dense material sank while lighter material rose to the surface during the early geological history C) molten lava oozes out between two tectonic plates that are slowly moving apart D) oceanic crust sinks below continental crust at a tectonic plate boundary
In binary neutron star systems, the orbits are expected to slowly decay, eventually resulting in a merger of the neutron stars. Where does the orbital energy go?
A) It is lost to friction. B) It is emitted as gamma-rays. C) It is emitted as neutrinos. D) It is emitted as gravity waves. E) It is converted to mass.