Which of the following statements about rich clusters of galaxies (those with thousands of galaxies) is not true?
A) They are sources of X-ray emission due to the presence of hot, intergalactic gas.
B) There likely have been numerous collisions among the member galaxies at some time in the past.
C) Galaxies in the central regions are predominantly spirals, while elliptical galaxies roam the outskirts.
D) They often have a very large, central dominant galaxy near their center, perhaps formed by the merger of several individual galaxies.
E) The speeds of the galaxies in the cluster indicate that most of the cluster mass is dark matter.
C
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Which of the following is true about low-mass stars compared to high-mass stars?
A) Low-mass stars are cooler and less luminous than high-mass stars. B) Low-mass stars are hotter and more luminous than high-mass stars. C) Low-mass stars are cooler but more luminous than high-mass stars. D) Low-mass stars are hotter but less luminous than high-mass stars. E) Low-mass stars have the same temperature and luminosity as high-mass stars.
Two harmonic sound waves reach an observer simultaneously. The observer hears the sound intensity rise and fall with a time of 0.200 s between the maximum intensity and the succeeding minimum intensity
What is the difference in frequency of the two sound waves? A) 10.0 Hz B) 0.200 Hz C) 5.00 Hz D) 2.50 Hz E) 1.25 Hz
Light not only has wavelike properties, but also has particle-like properties. What are these "particles" of light called?
a. quarks c. photons b. wavicles d. etherons
The Doppler technique can be used to measure the orbital period of a planet by
A) measuring the asymmetries in the velocity curve. B) measuring the amount by which the starlight is reduced when the planet transits. C) measuring the speed at which the star orbits the mutual center-of-mass of the star and planet. D) measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak.