Temperature, Heat, and Cooling Curves
Monday I showed a 1980 set of videos on heat and temperature by the Ontario Educational Communication Authority that was acquired by the MITC in VCR format circa 1993. Those videos remain one of the best introductions to temperature and heat which is comprehensive and fits into a 50 minute period comfortably.
Wednesday I ran a series of temperature demonstrations. This term the coconut oil was placed in the refrigerator in the morning, and melted at under 20°C. I also briefly mentioned three of the ways heat moves.
Thursday I used cups of three different materials: metal, glass, and Styrofoam. The morning session saw some groups abandoning data recording after they had ten to twelve data points - only ten minutes into the cooling. The trend appears linear at this point and I had to ask them to continue taking data. In the afternoon I went ahead and was more careful in noting that the data would take time and would slow down but would not stop. I noted the need to change the time interval as the water cooled.
As can be seen on the final board, I used the data not to introduce Newton's law of cooling per se but as a platform for looking at mathematical models. At 8:00 neither a linear nor a polynomial well fit the data. The same held true for 11:00. Both linear and polynomial solutions imply a time at which the water reaches zero degrees Celsius and freezes into ice. I then introduced a modified and simplified exponential decay as can be seen above and showed that this well modeled the data, including leveling off at or just above room temperature.
Temperatures
Wednesday I ran a series of temperature demonstrations. This term the coconut oil was placed in the refrigerator in the morning, and melted at under 20°C. I also briefly mentioned three of the ways heat moves.
Thursday I used cups of three different materials: metal, glass, and Styrofoam. The morning session saw some groups abandoning data recording after they had ten to twelve data points - only ten minutes into the cooling. The trend appears linear at this point and I had to ask them to continue taking data. In the afternoon I went ahead and was more careful in noting that the data would take time and would slow down but would not stop. I noted the need to change the time interval as the water cooled.
Emylane tracks temperature for cooling in a Styrofoam cup
Ashley and Jackleen used a metal pail
I tracked data in Desmos in the back of the room
Morning left board
Shirlynn and Shrue
The wait is long: Gary stretches out while Elianson tracks the time
As can be seen on the final board, I used the data not to introduce Newton's law of cooling per se but as a platform for looking at mathematical models. At 8:00 neither a linear nor a polynomial well fit the data. The same held true for 11:00. Both linear and polynomial solutions imply a time at which the water reaches zero degrees Celsius and freezes into ice. I then introduced a modified and simplified exponential decay as can be seen above and showed that this well modeled the data, including leveling off at or just above room temperature.
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