At what speed will a car flip over when it slides sideways into a curb? (Thanks to Reynier Cruz-Torres of MIT for suggesting the question.)

How much is a mole of people? Consider mass, area, power, and food requirements. Make appropriately silly comparisons. (Thanks to Bryan Suits of Michigan Technical University for suggesting the problem.)

Look for the answers online at under “Browse,” at the very end of the current issue.

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).

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