What makes white-dwarf supernovae good standard candles?
A) They are very bright, so they can be used to determine the distances to galaxies billions of light-years away.
B) They should all have approximately the same luminosity.
C) They occur so frequently that we can use them to measure the distances to virtually all galaxies.
D) We have had several occur close to us in the Milky Way, so we have been able to determine their luminosities very accurately.
E) both A and B
E
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Indicate whether the statement is true or false
A stone is lifted and released so that it falls to the ground. According to Aristotle, it fell because
A) of friction. B) of gravity. C) its natural motion is to fall. D) of electrical attraction. E) of its inertia.
The loop’s front end has emerged from the field.
A. forward (in the +x direction). B. backward (in the -x direction). C. zero. D. some other direction (specify).
If body P, with a positive charge, is placed in contact with body Q (initially uncharged), what will be the nature of the charge left on Q?
a. must be greater in magnitude than that on P b. must be equal in magnitude to that on P c. must be negative d. must be positive