Excerpted from Thinking Physics by Lewis Caroll Epstein
Insight Press, 614 Vermont St., San Francisco, CA 94107-2636
www.appliedthought.com/InsightPress
Used with Permission
A bunch of flies are in a capped jar. You place the jar on
a scale.
The scale will register the most weight when the flies
are
a) sitting on the bottom of the jar
b) flying around inside the jar
c) The weight of the jar is the same in both
cases.