Too many Americans are overweight. If we could somehow transform all of that unwanted fat into fuel, how much gasoline could we replace? How useful would that be?
On hot days we can see shimmering images and mirages. At what angle of incidence does a light ray traveling in ambient air totally reflect from a layer of hot air?
Look for the answers online at tpt.aapt.org. Question suggestions are always welcome! For more Fermi questions and answers, see the now available Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin, by Lawrence Weinstein (Princeton University Press, 2012).
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