Date: Mon Apr 30 11:24:21 2007

Author: Dennis C. Henry

Subject: Archimedes with variable-density liquid


A colleague has asked for suggestions on a demonstration/experiment
that shows how an object with density less than water (or another
liquid) floats with noticeably varying fractions exposed as one
varies the density of the liquid in real time. He thought about
adding salt to water while watching a piece of plastic or other
"bobber" rise a measurable amount. I don't know how easy it is to
get salt to dissolve in progressively saltier water, particularly
without stirring or heating. Of course, if one moves the object from
one container to another of liquids of different densities, it is
easy to see the effect of fluid density. I suggested the Cartesian
diver as a related demonstration, and this may be closer to his
objective of dealing with the effects of less obvious forces.


Dennis C. Henry Office Location: 213 Olin Hall
Professor and Chair of Physics Office phone: (507) 933-7314
Gustavus Adolphus College Office fax: (507) 933-6104
800 West College Avenue Home phone: (507) 931-2784
St. Peter, MN 56082-1498