posted by Katherine on .
Take two Styrofoam cups, partially fill them with equal amounts of cold water, and drop
equal amounts of ice into each cup to obtain a mixture of ice and water.
a. Stir the water and ice mixture in one of the cups vigorously with a nonmetallic
stirrer until all of the ice has been melted. Note the time that it takes to melt all
b. Set the second cup aside and observe it every 10 minutes or so until all the ice has
melted. Note the time that it takes for all the ice to melt.
c. How do the times compare? Where is the energy coming from to melt the ice in each cup.
Have you performed the experiment? What did you find out?
The answer to c. may not be what you think, or what the teacher thinks.
The energy of hand stirring is negligible compared to another source. Stirring affects convective heat transfer rates.