The Heat is On

Setup

The materials I chose for this experiment were brown paper, cheese cloth, a cotton washcloth, and a plastic ziplock bag.  I anticipated the plastic bag and the washcloth being the best insulators.  I hypothesized the plastic bag would trap in the most heat as it is similar to plastic wrap, a material used for locking in heat and preserving food.  Also, I figured the wash cloth would work similarly as cloths are sometimes used in place of pot holders to pick up hot food.  I hypothesized that the mug with the cheesecloth would be the coolest of the four because it was covered with the most porous material.  I also expected that each of the materials would be slightly dampened by rising heat.  

Results

I was correct in hypothesizing the plastic bag would retain the most heat as that mug dropped the smallest amount of degrees (see Appendix A).  I was incorrect in guessing though, that the cheesecloth would let out the most heat.  It was the second hottest mug after thirty minutes.  I was also incorrect in guessing the materials would become moist from the rising heat.  The water must not have been hot enough to cause the heat to rise up as steam.  

If I was choosing one of these four materials to insulate something I wanted to keep warm, I would choose the plastic.  If however, I was trying to cool down a substance,  the brown paper would be the most effective or no insulator at all.  “Heat is the measure of of the internal energy that has been absorbed or transferred from one body to another” (Tillery, Enger, & Ross, 2008).  The brown paper was able to better decrease the internal energy of the water in the mug while the plastic served as a better insulator, maintaining the internal energy.  

Questions

Which of the three methods of heat transfer did the materials encourage or discourage? How do you know? Support your response with evidence from the resources.

Conduction

The ceramic mug would have acted as a conductor for the transfer of the heat from the water.  The mug was cooler than the water inside so some of the heat transferred into it, cooling down the temperature of the water and heating up the mug.  “Anytime there is a temperature difference, there is a natural transfer of heat from the region of higher temperature to the region of lower temperature” (Tillery, Enger, & Ross, 2008).  Since I measured a temperature change, I know that conduction took place.  

Convection

Convection took place in the water.  As the water cooled, it became denser and fell.  The hot water rose to the top.  “In fluids, expansion sents the stage for convection.  Warm, less- dense fluid is pushed upward by the cooler, more -dense fluid around it” (Tillery, Enger, & Ross, 2008).  

What other materials might you choose if you were to repeat the experiment? Which of these do you believe would be the best insulators? Why?

I would like to try foil versus plastic wrap.  I think the foil would be more effective at insulating the mug over the plastic because the plastic is more porous.  I would also like to try a piece of white paper versus a piece of black paper.  I know that white reflects sunlight which is why we wear lighter colors in the summer, but would it also reflect heat?  

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