The Heat is On

Introduction

The three types of heat transfer are conduction, radiation, and convection. Conduction is the transfer of energy from atom to atom within a substance. An example of conduction is the warming of a metal spoon in a bowl of hot soup. Radiation is heat transfer by way of electromagnetic waves traveling through space. When electromagnetic waves come into contact with an object, the waves transfer the heat to that object. An example of radiation is the heat radiating from a light bulb. Convection, on the other hand, is the transfer of heat energy in a gas or liquid by movement of currents. An example of convection is the heat leaving a coffee mug as the currents of steam and air rise. This blog explores methods to reduce the amount of heat loss due to convection.

The Heat is On
This investigation sought out to determine which common household item would make the best insulator. I chose to test aluminum foil, newspaper, a plastic CD cover, and a cotton towel.

My hypothesis statement is as follows: If the release of steam and air causes loss of heat, and if plastic will trap the steam and air inside the mug, then the plastic CD cover will make the best insulator.

Materials:
four identical coffee mugs
aluminum foil
newspaper
plastic CD cover
a cotton towel
four rubber bands
a measuring cup
a thermometer
a timer
hot water.

Procedure
1. Place the four mugs in a row on a table and fill each mug with one cup of hot water.
2. Cover each mug with the materials being tested and secure each one with a rubber band.
3. Set the timer for 30 minutes.
4. Once 30 minutes have passed, record the temperature of the water in each mug with a thermometer.

Results:

Temperature Material
96 degrees F Aluminum foil
100 degrees F Cotton towel
106 degrees F Newspaper
102 degrees F Plastic CD cover

Conclusion
The newspaper provided the best insulation of the warm water in the coffee mug. My hypothesis was not correct.

QUESTION
Which of the three methods of heat transfer did the materials encourage or discourage?
Although the plastic CD cover did stop the currents of steam and air from rising, the heat then escaped from the plastic CD cover as radiation. This was also true of the aluminum foil as the plastic CD cover and aluminum foil were warm to the touch when removed from the mug. "A hot object, however, emits more energy than it absorbs from the colder object, and the colder object will absorb more energy from the hot object than it emits. There is, therefore, a net energy transfer that will take place by radiation as long as there is a temperature difference between the two objects." (Tillery et al, 2008, p. 88) Transfer of heat by convection was not present in this investigation because none of the tested materials actually touched the warm warm water. The towel and the newspaper discouraged conduction because these materials are not good conductors of heat. As it turns out, the newspaper provided the best insulation for the coffee mug.

I did not experience any challenges with this investigation.

Newspaper, a recyclable material, is an excellent insulator. It is currently used as a safe insulator in buildings. In fact, once this investigation was completed, I discovered that there are even instructions on how to make your own newspaper insulation on the Internet. Known as cellulose insulation, it provides a less expensive, safer alternative to its leading competitor which is fiberglass.

This investigation allows students to investigate ways to prevent heat loss.
"Most insulating materials are good insulators because they contain many small air spaces…not because of the material they are made of…" (Tillery et al, 2008, p. 86)
The discussion on ways to prevent heat loss can be expanded to prompt discussions on current issues such as recycling, government regulations for insulation in homes, and global warming.

References

Tillery, B.W., Enger, E.D., & Ross, F.C. (2008). Intergrated Science (4th ed.). New York: McGraw Hill