Every fall, my husband tries varying layers of clothing trying to find the right combination to stay warm on those cold, frosty mornings of hunting. Therefore, for this week’s experiment, I chose to test the various fabrics used to make thermal underwear. I tried a pair of those old fashioned, typical thermals that has been around for years. I tried a pair of fleece-type thermals, and a pair that the threads are hollow, mimicking polar bear fur. I also tested denim and camouflage pants, both worn to hunt and work outside in the winter.
I thought that the denim would be the worst, while the thicker fleece-type thermals would be the best insulator, just because it was thicker. The results were within a couple of degrees of each other. The fleece-type thermals were the best, but by just one degree; denim was the worst but only by two degrees.
Therefore, I redid the experiment trying a few other materials, I kept the fleece-type thermals, added a terrycloth dishtowel, a fleece baby blanket, a double layered flannel blanket, and Saran Wrap. This time I thought that the much thicker fleece blanket would be the best, because good insulators have air pockets that would slow the conduction of heat (Tillery, Enger, & Ross, 2008). I thought that the plastic wrap would be the worst.
I was right in that the fleece baby blanket was the best, but by only one degree. All the others, including the plastic wrap were the same temperature.
I think that all three types of heat transfer are at work in this experiment. Radiation because all things that have heat radiate (Tillery, Enger, & Ross, 2008). Conduction, because the molecules of water “bump” into the molecules in the air in the mug transferring energy, and then the air molecules transfer energy to the molecules in the material covering the mug, and they onto the air above the mug. In addition, heat is conducted out through the sides and bottom of the mug. The plastic wrapped mug that kept the heat as well as most of the other materials makes me think that convection is at work too. Warm water and air rises, as it hits the plastic wrap, it condensed and fell back in, and getting warmed back up by the hotter water and the hot mug.
If I were to do this with my students, I think I would have them try different materials that they brought in, as well as some I would provide, and let them compare their results. I would then give them a challenge to take what they learned and what they know about heat transfer to combine materials to design the best insulators that would keep them roasty, toasty warm on those cold frosty mornings of hunting. I have many students that hunt; I think that they would find this challenge intriguing and relevant to their lives.
I wonder which material would keep things cold as well as hot. Would it be the same materials?
I enjoyed reading your post. I liked how you personalized your experiment to make it meaningful to you, rather than just doing an experiment for assignment's sake.
ReplyDeleteIs it safe to say that your husband will be wrapping up in a fleece baby blanket next fall when he goes hunting? :) How do these materials compare to the materials he already uses while hunting.
Great question about if the same materials would work the same way for lower temperatures.
Janie
Probably not, but he does have some fleece pajama pants that he uses as one of his many layers.
DeleteI probably have enough baby blankets to make him an outfit, but it would not be very camo. :)
Georgianna,
ReplyDeleteI really liked you experiment also. I believe that you achieved similar results as mine, it really does not matter what you cover the cup with as long as it traps air in the cup over the water. Air is a great insulator and is probably influencing the test too much.
Sincerely,
David