Heat Transfer Experiment

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?

Guided Inquiry and Momentum

I chose the question: How does steepness of a slope and mass affect a collision outcome? My plan was to let a Hot Wheel car roll down a ramp and collide with a marble at the bottom, and then measure the distance the marble rolled. The experiment would be repeated with the three marbles of different masses--a small, medium, and large. I would then make my ramp steeper and repeat the experiment. My hypothesis was that the steeper the ramp the more velocity and the further the marble would roll. The more mass the marble had the less distance it would roll.
With two toddlers in the house and cars involved, it became a family experiment. It took some trial and error before we found the right combination of ramp material and Hot Wheel car that would go down the ramp in a straight enough line to hit the marble at the bottom. We rolled the car down the ramp three times for each size marble and measured the distance it rolled. We then raised the ramp height and repeated the experiment. (My kids had a grand time and were very involved--showing that such projects can be engaging and even exciting).
Our experiment proved my hypothesis correct. I was surprised at the difference traveled by the marbles. The smallest marble went way further than the large one, by about 100 cm.
I wonder if we should have used a different object than marbles--something that would not have rolled. If I were to use this in the classroom, I would use something other than marbles as they rolled quite far and would be a challenge to follow and measure the distance traveled without crossing the paths of others, or running out of room for several groups to be working.
To make it more engaging, there could be a competition as to which group could get the object to go the farthest. They could also add mass to the cars going down the ramp.
To connect to student lives, we could make the connection to playing football--it takes more force to move a larger player and stop a larger player.
We could also talk about car crashes--the faster one is traveling; the more damage done to the car, the object hit, and the people involved.
If I did this experiment with students I would hope they would learn more about how velocity and mass are related to momentum--that it takes more velocity and mass to move larger objects. The slower the velocity the less of an impact and the less momentum.
Did I achieve this goal? With me, it solidified these concepts. I believe it would help students as well.