# Physics 212, Extra Credit for Week #4: due Jan 13, 1998, at 7 PM

Build a better coffee mug.

This project may be done by teams of 1-3 individuals. The goal is to design and build an insulated container for hot liquids which beats a standard styrofoam cup. You may use any materials you wish, as long as you do not simply employ a commercial coffee mug; you must add a significant contribution to any pre-existing object you use.

The container you build must hold at least 6 ounces and at most 1 quart of liquid. It must be small and light enough for an ordinary person to hold and lift easily. You may not insert heating devices into the container; it should keep liquid warm in a passive manner.

Describe carefully the container you design and build. Explain in detail your choices for the materials and construction. Why should your mug be better than ordinary ones? Include a drawing of the finished object, and indicate the cost of any items you purchased for this project.

After you have built a container, you must test it against existing mugs; find an ordinary ceramic coffee mug, and a styrofoam cup. Boil some water (or coffee), and pour equal amounts into each of the three containers. Place the containers into a refrigerator or freezer for 10 to 20 minutes (adjust the length of time, if necessary, so that the results allow a fair comparison). Remove the containers from the cold, and measure the temperature of the liquid in each. Use a single thermometer, and measure temperatures in the following order: T(ceramic), T(styrofoam), T(yours), T(yours), T(styrofoam), T(ceramic). Give the thermometer time to reach equilibrium with the liquid in each cup -- perhaps 30 to 45 seconds will do. Average the two measurements from each container. Repeat the procedure so that you have two trials.

Does your design keep liquid warmest?

Submit a report which contains the pictures and descriptions of your experiment, as well as the results. You may also include interesting items you discovered during the course of the procedure.