The figure above shows how the luminosity of supernovae changes over time. About how long does it take a white dwarf supernova to decrease in luminosity by a factor of 100 from its peak?
A) 300 days
B) 200 days
C) 100 days
D) 25 days
B) 200 days
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A 120-g rubber ball is thrown with a speed of 10 m/s at an oncoming 900-kg car which is approaching at 30 m/s, and undergoes a one-dimensional elastic collision with the car. What is the speed of the ball after the collision?
A) 10 m/s B) 30 m/s C) 40 m/s D) 50 m/s E) 70 m/s
In order for a telescope to produce a large magnification one would select lenses of
A. short focal length for both objective and eyepiece. B. large focal length for the objective and short focal length for the eyepiece. C. short focal length for the objective and long focal length for the eyepiece. D. large focal length for both objective and eyepiece.
To calculate an object’s heat capacity, we take its specific heat and
A. multiply by the object’s mass M. B. divide by the object’s mass M. C. multiply by the molar mass MA of the object’s molecules. D. divide by the molar mass MA of the object’s molecules. E. multiply by the mass m of one molecule in the object. F. divide by the mass m of one molecule in the object. T. do something else (specify).
What charge appears on the plates of a 6.0-?F capacitor when it is charged to 40 V?
A) 60 ?C B) 120 ?C C) 180 ?C D) 240 ?C E) 350?C