When examining a spectrum of a particular galaxy, an astronomer notices that thespectral lines are shifted toward shorter wavelengths. What does this mean?
a) the element Helium is present in that galaxy
b) the galaxy is moving away from us
c) the galaxy is very likely to be one of the nearest galaxies to the MilkyWay
d) the entire Universe is contracting
e) the galaxy is rotating very rapidly
Ans: c) the galaxy is very likely to be one of the nearest galaxies to the MilkyWay
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In general, how does the size and location of a star's habitable zone depend on the star's mass?
A) the smaller (less massive) the star, the smaller and the closer-in the habitable zone B) the smaller (less massive) the star, the larger and the closer-in the habitable zone C) the smaller (less massive) the star, the larger and the farther-out the habitable zone D) The habitable zone is always about the same size, but its location moves inward for smaller stars.
Which of the following does not accurately describe what we observe toward the Galactic center?
A) at radio wavelengths, we see giant gas clouds threaded by powerful magnetic fields B) at infrared wavelengths, we see a massive stellar cluster C) at optical wavelengths, we see a cluster of old, red stars D) at X-rays, we see faint emission from an accretion disk around a black hole
How much electromagnetic energy is contained in each cubic meter near the Earth's surface if the intensity of sunlight under clear skies is 1000 W/m2?
a. 3.3 × 10^?6 J b. 3.3 J c. 0.003 J d. 10?4 J e. 3.0 × 10^5 J
A particle of kinetic energy 50 eV in free space travels into a region with a potential well of depth 40 eV. What happens to its speed?
A) It remains the same. B) It increases in the region of the well. C) It decreases in the region of the well. D) It cannot be determined from the information given.