Save the Ice Cube - Exploration

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Phriendly Physics Home - Invitation - Background - Demonstration - Exploration

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Purpose:

This exploration has a very direct and simple purpose: The participants each try to make a container which will keep an ice cube from melting for the longest time.

Materials:

Styrofoam cups (with lids), plastic wrap, aluminum foil, cotton balls, paper bags, plastic bags, and so forth.
You will also need a scale of some sort if you want to keep the contest competitive.

Preparation:

The only thing to prepare in advance is to make sure you have a set of ice cubes which are completely frozen and all the same weight. You can do this by having miniature plastic cups, or just carefully measuring into a regular ice cube tray. Take a small container and pour the exact same amount of water into each container, and leave until they are completely frozen.

Parameters:

The groups can use whatever method they want to keep the ice cube cold—except they can't use a refrigerator, freezer, or more ice. Encourage the group to think about how heat gets to the ice cube and plan how to insulate  it.
They can have their choice of where to place it, and what to put it in. Remind them of how heat gets to it—i.e. Is it better to put it in the light or in the dark?

Evaluating:

After some set period of time (which could be one or two hours), the groups should all collect their ice cube savers. To be competitive, pour off the melted water, and weigh each partially-melted ice cube in the same container. The heaviest remaining ice cube is the winner.