Video: Understanding the Effects of Insulation

Amelia wraps three beakers in different materials. She then fills the beakers with water at 100°C. She measures the temperature of the water in each beaker 30 minutes later. Her results are shown in the table. What material was the best insulator? What material was the worst insulator?

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Video Transcript

Amelia wraps three beakers in different materials. She then fills the beakers with water at 100 degrees Celsius. She measures the temperature of the water in each beaker 30 minutes later. Her results are shown in the table. What material was the best insulator? What material was the worst insulator?

Okay, so what we have here is an experiment involving three beakers of water. So let’s say that here are our beakers. Now we’re told that they’re wrapped in different materials. One of the beakers is wrapped in felt, another is wrapped in cardboard, and the third beaker in aluminum foil. Following this, all the beakers are filled with water at 100 degrees Celsius, that’s boiling hot. Then, 30 minutes later, the temperature of the water in each of the three beakers is measured. That measure temperature is recorded in the bottom row of this table of data. Based on all this, we want to know which of these three materials was the best insulator and which one was the worst.

To figure this out, we want to know what an insulator is in the first place. An insulator is a material that resists the transfer of heat. We’re all familiar with insulators. For example, each one of us has probably used an oven mitt, which is an insulating material in order to handle hot dishes on the stove. So of these three materials — felt, cardboard, and aluminum foil — the best insulator will be the one that resists the transfer of heat out of the water the most. The water in the beaker with the best insulator will be the water that decreases in temperature the least; that is, it will retain the most of its heat energy. That means that the highest water temperature will indicate the best insulated beaker.

Looking at our table, we see that in the bottom row 38 degrees is the highest temperature of the water after 30 minutes. That tells us that the beaker wrapped in this material cardboard is best insulated. So we’ve write that down as our answer for the best insulator. It’s cardboard. And then, we move on to consider what material was the worst insulator. The worst insulator will do the opposite of a good insulator. It will let lots of the heat of the water disperse. The result of that heat dissipation will be that the water temperature will be lowest.

Looking again at the bottom row of our data table, we see that the lowest measured water temperature is 25 degrees Celsius. That corresponds to the beaker wrapped in aluminum foil. Because this water has cooled the most over the half-hour interval, 75 degrees Celsius, that means it’s insulated the least. Or in other words, it’s surrounded by the worst insulator. And that worst insulator is aluminum foil based on the fact that the water in the beaker wrapped in aluminum foil cooled down the most.

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