How many person-hours are spent listening to graduation speeches each year? How long is this in lifetimes?
If we are stuck in the middle of a 100-m radius frozen (i.e., frictionless) lake, how long would it take us to escape, using just a small handheld, electric fan?
Look for the answers online at tpt.aapt.org
Question suggestions are always welcome!
For more Fermi questions and answers, see Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin, by Lawrence Weinstein (Princeton University Press, 2012).