Which is more granular (quantized), a stream of water or a stream of light? (Thanks to Gary White of The Physics Teacher for suggesting the question.)
How many coffee beans do Americans consume yearly? (Thanks to Chuck Adler of St. Mary's College of Maryland for the question.)
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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