During the Heat is On experiment, all three methods of heat transfer were present. The hot water heated the air within the cup by radiation. The air at the surface of the water was heated by emitted heat from the water so radiation took place. The rest of the air within the cup was heated by convection. Hot air that was heated by contact with the water rose inside the cup (hot air is less dense than cold air and, thus, rises). When the hot air rose, the colder, denser cold air sunk inside the cup to be heated through conduction by the hot water. This cycle continues, heating all of the air inside the cup (Tillery, Enger, and Ross, 2008). When the hot air rises in the cup it comes in direct contact with the cover material and transfers heat to the material through conduction. The heat then passes through the material to the surrounding outside air through radiation.
When I conducted this experiment, I used wax paper(13 degree change), aluminum foil (15 degree change), plastic wrap (11 degree change), and no covering (24 degree change). If I were to do this experiment again, I would try using fabric and glass as a cover to see if their insulating properties are different than the insulators that I originally chose. I think that the glass would prove to be the best insulator because it would not allow any steam to escape from the cup as fabric might. Glass, like air, however, has a very low specific heat which would indicate that it will change temperature very easily and would transfer heat more readily (Tillery, Enger, and Ross, 2008). This would indicate to me that, after air, glass would transfer the heat from the cup fastest; faster even than the aluminum which has a higher specific heat.
I would like to try this experiment again with an object wrapped in the different materials so that the air pocket inside the cup could be removed from the experiment. I think a hotdog would be a good material to use because hotdogs are uniform in shape, they are easy to heat, and also easy to wrap in the experimental materials. I think that the hotdogs would cool faster than the water because water has a very high specific heat which requires a great deal of energy to change its temperature (Tillery, Enger, and Ross, 2008).
I think that this exact experiment could be used in my classroom. A wide variety of materials could be available for students to test out as potential insulators and conductors. To make this experiment more interesting for my students, I would present them with a scenario in which I had guests over to my house and I was trying to keep our dinner warm while everyone finished up their appetizers. I couldn’t find an appropriate covering for the food, everything got cold very quickly, and dinner was ruined (other scenarios could be used). I will ask my students for their advice on the matter and then invite them to try out their ideas. Once students had experience with this activity, I think a good extension of the lab would be to have students design their own thermos in which they have to sustain a specific water temperature for a given amount of time. Students would have to use their knowledge of heat transfer (all forms) to eliminate any possible loss of energy.
I would like students to learn about the three different methods of heat transfer, the different types of conductors and insulators and their properties, and I would like them to gain some experimental design experience. I achieved all of these goals while I was engaged in this activity.
Tillery, B. W., Enger, E. D., & Ross, F. C. (2008). Integrated science (4th ed.). New York: McGraw-Hill.
Sunday, May 30, 2010
Sunday, May 16, 2010
Engaging in Guided Inquiry
The question that I chose to explore was: Which pendulum will come to rest more quickly—a lighter pendulum or heavier pendulum? In order to set up this experiment I had to access my background knowledge of pendulums; for instance, what is a pendulum? I had to decide how I was going to create my pendulum using the materials that were provided to me in my science kit. I chose to use the small, lighter washer and the large, heavier washer, along with the black string. I knew that I needed to keep the length of the pendulum and the height that I pulled the pendulum constant so that any differences I observed in swing time could solely be attributed to the weight of the pendulum. From prior experience with pendulums, I also knew that I would want an area that the pendulum could freely swing without bumping into other objects because this would change the period of the pendulum and skew my data.
I hypothesized that the lighter pendulum would come to rest more quickly because it has less mass and therefore less momentum and less potential energy. Because this pendulum has less potential energy, it also then has less energy to convert to kinetic energy which would maintain its motion. What I observed through this experiment was that the heavier pendulum swung for an average time of 3.32 minutes whereas the lighter pendulum swung for an average time of 1.33 minutes. To get these averages I conducted three trials of each weight pendulum and then averaged the time results.
I did not experience any challenges in this activity but there were a few things that I incorporated into the lab that were not provided for me. I needed to secure the pendulum to my counter top so I introduced tape into the lab. Also, I wanted an easy way to take the washers on and off of the pendulum so I introduced a paperclip to the end of the pendulum so that washers would easily be taken on and off without having to untie and retie anything. This did not affect the outcome of the investigation because the same paperclip was used with both washers, therefore, not altering the overall net difference in weight between the washers.
To get a different result with my students or to use this same experiment in different ways, I might simply ask students "What affects the period (or swing) of a pendulum?" Students would get to change different aspects of the pendulum including the weight the length, and the height that they pull it back.
To make this activity more engaging I might bring up the amusement ride with the giant ship. I could challenge the students to engineer the ride so that the ride lasts longer or rocks back and forth the fastest. They would have to experiment with the different variables to identify what would make the ride longer or slower or faster.
What I would like to students to take away from an activity such as this is I would want them to be able to plan and set up an experiment to test their hypothesis, carefully write a procedure, make observations both qualitatively and quantitatively, and draw conclusions from their data and observations. I would additionally like students to be able to apply their new knowledge in a real-world setting. I believe that if I have been practicing inquiry with my students on a regular basis then they will be ready for a guided inquiry activity such as this and will, thus, walk away with the knowledge and skills that I have sought for them.
I hypothesized that the lighter pendulum would come to rest more quickly because it has less mass and therefore less momentum and less potential energy. Because this pendulum has less potential energy, it also then has less energy to convert to kinetic energy which would maintain its motion. What I observed through this experiment was that the heavier pendulum swung for an average time of 3.32 minutes whereas the lighter pendulum swung for an average time of 1.33 minutes. To get these averages I conducted three trials of each weight pendulum and then averaged the time results.
I did not experience any challenges in this activity but there were a few things that I incorporated into the lab that were not provided for me. I needed to secure the pendulum to my counter top so I introduced tape into the lab. Also, I wanted an easy way to take the washers on and off of the pendulum so I introduced a paperclip to the end of the pendulum so that washers would easily be taken on and off without having to untie and retie anything. This did not affect the outcome of the investigation because the same paperclip was used with both washers, therefore, not altering the overall net difference in weight between the washers.
To get a different result with my students or to use this same experiment in different ways, I might simply ask students "What affects the period (or swing) of a pendulum?" Students would get to change different aspects of the pendulum including the weight the length, and the height that they pull it back.
To make this activity more engaging I might bring up the amusement ride with the giant ship. I could challenge the students to engineer the ride so that the ride lasts longer or rocks back and forth the fastest. They would have to experiment with the different variables to identify what would make the ride longer or slower or faster.
What I would like to students to take away from an activity such as this is I would want them to be able to plan and set up an experiment to test their hypothesis, carefully write a procedure, make observations both qualitatively and quantitatively, and draw conclusions from their data and observations. I would additionally like students to be able to apply their new knowledge in a real-world setting. I believe that if I have been practicing inquiry with my students on a regular basis then they will be ready for a guided inquiry activity such as this and will, thus, walk away with the knowledge and skills that I have sought for them.
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