Newton’s Law of Cooling Exploration

Lab Experiment

Divide the students into groups based on the equipment available.If using TI CBLs, the recommended group size is two; if using thermometers, the recommended group size is three (data gatherer, data reorder, and timekeeper).

Materials

The following materials will be used:

• Styrofoam cups (with and without lids)
• Ceramic mugs (with and without lids)
• Insulated mugs (with and without lids)
• A source of hot water (the best source is a 10 cup coffee pot)
• Temperature measuring devices: TI graphing calculators (TI-82, -83, -85, or -86) with TI CBLs or thermometers

Equipment Setup

If using TI graphing calculators with CBLs the following programs need to be entered into the specific calculators.Each calculator will need the COOL and the GETDATA programs.

For TI-82, -83, and –85 calculators:

Program	Description
PROGRAM:COOL
{1,0}®L1:SEND(L1)	Rest, clear all probes
{1,1,10}®L1:SEND(L1)	Set temperature probe, measure in °C
Disp “INTERVAL BETWEEN”
Disp “READINGS (SECS)”
Prompt S	Read temperature every S seconds
Disp “TOTAL NUMBER OF”
Disp “DATA POINTS”
Prompt N	Collect N measurements
Disp “TOTAL TIME (HRS)”
Disp S*N/3600
Disp “ PRESS TRIGGER TO”
Disp “START”
{3,S,N,1,0,0,0,0,1}® L1:SEND(L1)
prgmGETDATA

For TI-82 and –83 calculators:

Program	Description
PROGRAM:GETDATA
Get(L2):Get(L1)	Get temperature data, then time data
Plot1(Scatter,L1,L2,.):ZoomStat	Plot the data in a scatter plot

For TI-86 calculators:

Program	Description
PROGRAM:GETDATA
Get(L2):Get(L1)	Get temperature data, then time data
Plot1(1,L1,L2,1):ZData	Plot the data in a scatter plot
Scatter L1,L2

For TI-85 calculators:

Program	Description
PROGRAM:COOL
{1,0}®L1:Output(“CBLSEND”,L1)	Rest, clear all probes
{1,1,10}®L1:Output(“CBLSEND”,L1)	Set temperature probe, measure in °C
Disp “INTERVAL BETWEEN”
Disp “READINGS (SECS)”
Prompt S	Read temperature every S seconds
Disp “TOTAL NUMBER OF”
Disp “DATA POINTS”
Prompt N	Collect N measurements
Disp “TOTAL TIME (HRS)”
Disp S*N/3600
Disp “ PRESS TRIGGER TO”
Disp “START”
{3,S,N,1,0,0,0,0,1}®L1
Output(“CBLSEND”,L1)
prgmGETDATA
PROGRAM:GETDATA
Input “CBLGET”,L2
Input“CBLGET”,L1
0®xMin:max(L1)®xMax
0®yMin:max(L2)*1.4®yMax
Scatter L1,L2

Data Collection

The students will need to record the room temperature at the beginning of the lab.On the TI CBLs with TI graphing calculators, set the “INTERVAL BETWEEN READINGS (SECS)” to 60 and the “TOTAL NUMBER OF DATA POINTS” to 5.If thermometers are being used, have the students read the room temperature directly.Once these readings are completed, distribute the cups/mugs of hot water to the groups of students.Insert the temperature probe/thermometer into the hot water and allow approximately a minute it to stabilize to the temperature of the water.

Record the temperature of the water over the remaining class time.Be sure that the temperature probe or thermometer is in the water and not touching he side of the container.If using a TI graphing calculator with a TI CBL, set the “INTERVAL BETWEEN READINGS (SECS)” to 120 and the “TOTAL NUMBER OF DATA POINTS” to whatever number is needed to allow the students to finish recording data to just prior to the end of the class period.If using a thermometer, record data every two minutes.When recording the temperature of the water, the first temperature point is time = 0.

Note:The TI-82 calculator will automatically shutoff if no keys are depressed.If this happens during data collection, simply press the ON button and only the ON button; no data will be lost during this process.

If CBLs are used, the data is stored in the list files (L₁ and L₂) until needed.

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