Via the rotation curve method, we can estimate the mass of galaxies like M31 from
a. Doppler shifts of material at the edge of its disk and computing P = 2?r/v.
b. the distances of the Doppler shift points from its center.
c. Doppler shifts of material at the edge of its disk and computing P = 2?r/v and the distances of the Doppler shift points from its center.
d. It is impossible to estimate the mass of M31.
c
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The light from Polaris is 24.2 times less intense than the light received from Sirius. Which star is the truly brighter star, that is, emitting more visual light at its surface?
a. Polaris b. Sirius c. Neither, they emit the same amount at their surfaces. d. This cannot be determined based upon the information given.
Suppose you built a scale-model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend
A) several kilometers B) a few meters C) several centimeters D) to the Sun
Ernest Rutherford
A) observed back-scattering from nuclei. B) discovered radium and polonium. C) proposed the tiny central nucleus idea. D) invented the particle detector tube. E) proposed the plum-pudding model.
By what factor is the intensity of sound at a rock concert louder than that of a whisper when the two intensity levels are 120 dB and 20 dB respectively?
a. 1012 b. 108 c. 106 d. 1010 e. 1011