Which of the following is true of rich galaxy clusters?
A) They primarily consist of irregular galaxies.
B) More than 80 percent of their galaxies are spiral galaxies.
C) Less than 20 percent of their galaxies are E and S0 galaxies.
D) They often contain one or more giant elliptical galaxies at their centers.
D
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A guitar string 0.650 m long has a tension of 61.0 N and a mass per unit length of 3.00 g/m. (a) What is the speed of waves on the string when it is plucked? (b) What is the string's fundamental frequency of vibration when plucked?
What will be an ideal response?
Two stones, one twice the mass of the other, are dropped from a cliff. Just before hitting the ground, what is the kinetic energy of the heavy stone compared to the light one?
a) quarter as much b) half as much c) the same d) twice as much e) four times as much
The fusion of Li and N results in creation of
A) O and no energy transformed to other forms. B) He and energy transformed to other forms. C) He and no energy transformed to other forms. D) salami and cheese sandwiches. E) O and energy transformed to other forms.
In nuclear fusion,
A. many radioactive nuclei decay at once. B. the temperatures required are so high that it has never been accomplished on Earth. C. two smaller nuclei combine to form a larger nucleus. D. a large nucleus splits into smaller fragments.