Which of the following is not one of the three main strategies used to measure the mass of a galaxy clusters?
A) measuring the speeds of galaxies orbiting the cluster's center
B) studying X-ray emission from hot gas inside the cluster
C) observing how the cluster bends light from galaxies located behind it
D) measuring the temperatures of stars in the halos of the galaxies
D
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The ? alloys of titanium are precipitation-hardened by the precipitation of the _________phase by heat-treating at a temperature well below the ?-transus.
Fill in the blank(s) with the appropriate word(s).
Almost half of all known millisecond pulsars are found in what type of object?
A) giant molecular clouds B) open clusters C) globular clusters D) emission nebulae E) supernova remnants
A man 190. cm tall stands 25. m from a plane wall mirror. One meter in front of him sits his dog, 30. cm tall. What minimum mirror size is needed for the man to see all of his dog's reflection?
What will be an ideal response?
A device that measures absolute air pressure is called a
a. manometer b. barometer c. thermometer d. tire gauge e. none of the above