Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that
A) the star is a Cepheid variable.
B) the star is a member of an eclipsing binary star system.
C) the star is periodically ejecting gas into space, every 73 hours.
D) the star is a white dwarf.
B
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As you crawl toward the edge of a large freely-rotating horizontal turntable in a carnival funhouse, the angular momentum of you and the turntable
A) decreases. B) increases. C) remains the same, but the revolutions per minute decrease. D) decreases in direct proportion to your decrease in revolutions per minute. E) none of these
Even though Jupiter's moon Io is similar in size to our geologically dead Moon, it is more geologically active than the Earth. How can this be?
A) because Io orbits very close to Jupiter, it still has a lot of heat trapped inside from its formation B) Io is tidally heated by tidal forces exerted by the outer Galilean moons, which flex and distort its interior C) Io has much more radioactive decay occurring inside it than does the Earth D) Io is tidally heated due to its elliptical orbit, which causes the large tidal forces exerted by Jupiter to constantly change, flexing and distorting its interior
The symbol 0 1e is used to represent the ________.
A. proton B. positron C. antiproton D. neutrino E. electron
When static equilibrium is established for a charged conductor, the electric field just inside the surface of the conductor is
A) opposite to the field outside. B) equal to the perpendicular component of the field outside. C) equal to the field outside. D) zero. E) cannot be determined.