Thermal energy, also commonly known as heat energy, is the energy of vibrating or moving molecules. When a substance is heated, its atoms and molecules begin to vibrate. As the particles gain more and more energy they will vibrate more vigorously. These vibrating particles will then bump into other particles nearby and cause them to vibrate more. Substances that allow thermal energy to easily pass through them are called conductors. Atoms and molecules, the smallest particles of substance, are always in motion. The amount of heat transferred depends on the speed and the number of atoms or molecules in motion. The faster the particles move the higher the temperature is. The greater the amount of atoms or molecules in motion, the more heat they transfer. The motion of thermal energy is usually not visible.

Figure 1

Figure 2: thermometers are a common application of thermal energy.

Candles are also a common application of thermal energy. The wick of candles are absorbent; sort of like a towel. The actual candle wax and the wax that coats the wick is paraffin wax. Paraffin wax is a heavy hydrocarbon that is made from crude oil (the same oil gasoline comes from). When the candle is lit, you can probably see the wax around the wick melts. The absorbent wick then absorbs the wax and pulls it forward. The flame is being fueled by the wax, which then vaporized as it is being burnt. When you blow out a candle, the smoke that it emits is paraffin vapor that has condensed into a visible form.

Figure 3: Play-Dough model of a candle.

An experiment to test the thermal energy of a hand warmer each minute over a twenty-minute time period was then performed. The method used in this experiment was to keep track of time using a stopwatch and measure how much the hand warmer had using a thermometer. The timer was stopped after sixty seconds and the temperature was taken. This action was repeated twenty times. An electronic table was used to organize all the data observed. Before the timer started, the hand warmer was 25.1⁰C. After the first minute was over, the temperature had risen to 26.2⁰C. The temperature continued to rise until, at the fourteen minute mark (when the temperature was 42.6⁰C), the temperature of the hand warmer began to drop. After that the temperature had dropped to 40.3⁰C. At the twentieth minute, the temperature was 36.7⁰. In conclusion, the hand warmer had risen 17.5⁰C total.
Figure 4: Photo of the experiment being performed.
Figure 5: Table of data