The sky appears to be blue during the day because:
1.Air absorbs blue light less than other frequencies (i.e., acts like a blue filter).
2.Air molecules emit blue light after being struck by sunlight.
3.The sky reflects blue light from the oceans.
4.The temperature high in the Earth's upper atmosphere is 1000 K.
5.None of the above.
4
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In contradiction to the teachings of Aristotle, Galileo found that an object with no forces (and no friction) acting on it will ____
a. move faster and faster b. eventually stop moving c. move at a constant speed forever d. first increase and then decrease in speed e. first decrease and then increase in speed
The supernova that formed M-1, the Crab Nebula, was observed in:
A) 1572 AD by Tycho Brahe. B) 1604 AD by Johannes Kepler. C) 1054 AD by Chinese and Middle Eastern astronomers. D) 1006 by observers in the southern hemisphere. E) about 9,000 BC by all our ancestors.
You would be richest if your hunk of gold had a mass of one kilogram
A) on the moon. B) on Earth. C) Actually it wouldn't make any difference.
You have a choice between two lenses of focal lengths fa and fb = 2 fa to use as objective lens in building a compound microscope. If the magnification you obtain using lens A is Ma, what will be the magnification when using lens B?
A) Mb = 2 Ma B) Mb = 4 Ma C) Mb = 8 Ma D) Mb = Ma /4 E) Mb = Ma /2