Is thermal energy linked to mass, or material, or both? Here is a quick, qualitative activity that compares ceramic tiles to pennies. We will heat them to the same temperature, and compare their ability to warm a small amount of air.

Materials:

• 2 ceramic tiles
• about 25 pennies
• two styrofoam cups
• two index cards
• two zipper-seal plastic bags
• a container of hot water
• liquid crystal thermometer

If you have a scale, determine how many pennies are needed to equal the weight of the two tiles (it depends on both the pennies and the tiles, but is about 22).

Put the pennies and the tiles in sealed plastic bags, and soak these in the hot water for several minutes.

Pull out one of the bags and shake off the water. Then dump the contents into one of the styrofoam cups, trying not to get too much water in it. Cover part of the top with the thermometer, and cover the rest of the top opening with an index card. Observe how the temperature varies over the next few minutes. Then repeat with the contents of the other bag.

This experiment compares the heating ability of equal weights of stuff, that start at the same temperature. To the extent that the results are different, it must have happened because the materials are different.

This experiment makes the same point as the previous one (comparing the cooling ability of equal volumes of rock and water). The two experiments differ in many respects, however. Comment on the similarities and differences. Which was more convincing?

About thermal energy