How could we determine the amount of interstellar dust between us and a distant star?
What will be an ideal response?
The spectral lines would give us the temperature and luminosity of the star, but if much dust were present, the light would appear redder than the spectral class would let us expect. Also, the fainter it looks, compared to its estimated luminosity, the more dust is absorbing its light in transit.
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You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two?
A) There is no difference. B) The line in the faster rotating star is blueshifted. C) The line in the faster rotating star is redshifted. D) The line in the faster rotating star is broader. E) The line in the faster rotating star is narrower.
What is a selective surface?
What will be an ideal response?
What is indicated by a gasoline's octane rating?
A) the degree of branching in the gasoline hydrocarbons B) the degree at which the compound ignites C) the percentage of octane in the mixture D) a measure of how many degrees it takes to ignite a mixture of octane E) none of the above
A person would like to pull a car out of a ditch. This person ties one end of a chain to the car’s bumper and wraps the other end around a tree so that the chain is taut. The person then pulls on the chain perpendicular to its length, as shown in the picture. The magnitude of the force that the chain exerts on the car in this situation is
A. Much smaller than the force the person exerts on the chain. B. About equal to the force the person exerts on the chain. C. Much bigger than the force the person exerts on the chain.