Patty Fouks, age 16, of Deer Park, Wis., for her question:

WHAT EXACTLY IS HEAT?

Heat is a form of energy. Heat and energy cannot be seen but the work they do can.

Heat energy flows from a hot to a cold object when they are in contact. The rapidly moving atoms or molecules in the hot object strike the less energetic atoms or molecules in the cold object and speed them up. In this way, internal energy in the form of heat passes from a hot object to a cold object.

Heat is measured in two kinds of units: British thermal units (B.T.U.s) and calories.

One B.T.U. is the quantity of heat needed to raise the temperature of one pound of water one degree Fahrenheit. One calorie is the quantity off heat needed to raise the temperatures of one gram of water one degree Celsius.