What do we mean by the event horizon of a black hole?
A) It is the point beyond which neither light nor anything else can escape.
B) It is the center of the black hole.
C) It is the distance from the black hole at which stable orbits are possible.
D) It is the place where x-rays are emitted from black holes.
A) It is the point beyond which neither light nor anything else can escape.
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The Sun and the Moon have the same angular size. If the Sun is 400 times farther away from the Moon, the Sun must be ________ times the size of the Moon.
A. 400 B. 1/400 C. 4 D. 1/4 E. 4?
How does Mercury's magnetic field compare to our own?
A) Like Venus, Mercury has no detectable magnetic field. B) Like Mars and the Earth, it too has undergone polarity reversals. C) It is 1/100th as strong as ours, but does deflect the solar wind to some degree. D) It is amazingly strong, comparable to our own. E) It was predicted from Mercury's rapid rotation and molten core.
A conducting bar slides without friction on two parallel horizontal rails that are 50 cm apart and connected by a wire at one end. The resistance of the bar and the rails is constant and equal to 0.10 ?
A uniform magnetic field is perpendicular to the plane of the rails. A 0.080-N force parallel to the rails is required to keep the bar moving at a constant speed of 0.50 m/s. What is the magnitude of the magnetic field? A) 0.10 T B) 0.25 T C) 0.36 T D) 0.54 T E) 0.93 T
Features of the deep ocean basins include abyssal plains, ocean trenches, mid-ocean ridges, and seamounts—all of which are composed of
A) plutonic rock. B) granite. C) basalt.