How did Harlow Shapley determine where the center of the galaxy lies?
a. He plotted the distribution of open clusters.
b. He plotted the distribution of globular clusters.
c. He made star counts in every direction of the galactic disk.
d. He measured the amount of dust obscuration in every direction of the galactic disk.
b
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A player catches a ball. Consider the action force to be the ball against the player's glove. The reaction is the
A) player's grip on the glove. B) force of the glove on the ball. C) friction of the ground against the player's shoes. D) muscular effort in the player's arms. E) none of the above
A parallel-plate capacitor stores charge Q. The capacitor is then disconnected from its voltage source, and the space between the plates is filled with a dielectric of constant ? = 2 . What is the relationship between the stored energies of the capacitor, where PEi is the initial stored energy, and PEf is the stored energy after the dielectric is inserted?
a. PEf = 0.25PEi b. PEf = 0.5PEi c. PEf = PEi d. PEf = 2PEi
Who discovered the atomic nucleus in 1911?
a. Marie and Pierre Curie b. Henri Becquerel c. Ernest Rutherford d. Niels Bohr
Doubling the distance between sound source and a listener will change the intensity, as detected by the listener, by what factor?
a. 4 c. 1/2 b. 2 d. 1/4