Which of the following measurements can be made only by recording and comparing the amount of light received from an astronomical source at many different times?
A) the rate at which a variable star brightens and dims
B) the general shape of an interstellar cloud of gas
C) the color of a planet
D) the number of bright stars in a nearby star cluster
A) the rate at which a variable star brightens and dims
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Which of these Galilean satellites is most geologically active?
a. Io b. Europa c. Callisto d. Ganymede
A 1-kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about
A) 0.5 J. B) 1.0 J. C) 1.5 J. D) 2.0 J. E) more than 2.0 J.
There are other ways of expressing uncertainty besides significant figures. For example, suppose a quantity is known to have a value between 20.4 and 20.0, and our best estimate of the value is midrange at 20.2 . We could write the number as 20.2 +/? 0.2 and say that the number has a 1% uncertainty. We would also say it has 3 significant figures. If we square a number with 1% uncertainty (i.e.,
2 parts in about 200) and 3 significant figures, what results? a. A number with 1% uncertainty and 3 significant figures. b. A number with 2% uncertainty and 3 significant figures. c. A number with 2% uncertainty and 2 significant figures. d. A number with 1% uncertainty and 2 significant figures.
The creation of elements inside a star is called _______________
a. nucleosynthesis b. fission c. production d. transmutation