Which of the following is not evidence for dark matter?
A) gravitational lensing around galaxy clusters
B) X-ray observations of hot gas in galaxy clusters
C) the broad absorption lines found in the spectra of elliptical galaxies
D) the flat rotation curves of spiral galaxies
E) the expansion of the universe
E
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To the nearest percent, what fraction of an iceberg is submerged? (?ice = 917 kg/m3, ?sea = 1.03 × 10^3 kg/m3.)
a. 95% b. 93% c. 91% d. 89% e. 77%
An electron in a hydrogen atom makes a transition from the n = 4 to the n = 3 energy state. Determine the energy (in eV) of the emitted photon
a. 0.54 b. 0.66 c. 0.85 d. 1.51 e. 10.2
Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 3.0 m/s2 . What is the magnitude of the force exerted on the right cube by the middle cube in this case?
a. 12 N c. 24 N b. 18 N d. none of the above
The most striking example of solar variability was the
A) Dust Bowl drought of the 1930s. B) Maunder Minimum from 1645-1715. C) Sporer Minimum that doomed the Anasazi. D) fall of Rome. E) Joseph's seven lean years in the Old Testament.