Exploring heat transfer in mugs leads me to think about a dilemma that I have every year as a teacher which is my coffee or tea getting cold before I can get it drank. I chose to solve this dilemma by purchasing a coffee mug warmer, but I also could have explored using a lid of some sort to help keep my beverage warm. When choosing materials to top my mug and act as an insulator I naturally think about materials that are often used to hold or contain beverages or as insulators in the kitchen. I chose paper, corrugated cardboard, foil, and Styrofoam as the tops for my mugs.
I naturally expected the Styrofoam to act as the best insulator followed by the corrugated cardboard, then the foil and the paper to act as the worst. In conducting this experiment I found that I was mostly correct in my hypothesis of which topper would act as the better insulator. The Styrofoam was by far the best insulator and the paper was the worst. Where I was wrong was that the foil was a better insulator than the corrugated cardboard. I believed that the corrugated cardboard would act as a better insulator than the foil due to having more air pockets. They were very close in temperature, but the foil mug was warmer. This may have been due to the fact that the steam from the hot water built up on the corrugated cardboard causing it to become soggy. These results may also have been due what I feel was a flaw in the experiment. The mug with the foil was poured last and the mug topped with the cardboard was poured first. The small difference in time may account for the results. If I were to conduct this experiment again I would take an initial temperature for each mug and measure the change in temperature rather than just the end result. This would allow me to have more accurate results in measuring the change in temperature from the time the water enters each individual mug.
One way that I try to make this concept relevant to student lives is by having them explore why hot fudge sundaes come in plastic containers, milk shakes in Styrofoam, and blizzards in paper. The students then design and construct their own experiments to answer this question. Students may not care why their hot fudge sundae is in plastic, but who doesn't like to experiment with ice cream! In the end they are rewarded with ice cream!
I too am surprised by the foil in your experiment as it is a conductor of heat. I would assume that the corrugated cardboard, with its small pockets of air, would be a great insulator. The coverings for my mugs included a cotton towel, wool sock, plastic wrap, and foil. The foil was only second to the plastic wrap in terms allowing heat to escape the mugs.
ReplyDeleteYour activity with ice cream would definitely interest my students. This is something I may try this year as we cover heat transfers.
I never thought about the fact that ice cream is served in different containers, depending on the ice cream preparation. It doesn't matter where you get it, it is still served in styrofoam for milkshakes, plastic for sundae's, and paper for blizzards. Interesting analysis!
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