tp46 heat transfer

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Physics Labs with Computers, Vol. 2 Teachers GuideP46: Heat Transfer 012-06101C

SAFETY REMINDERS Wear protective gear.

Follow directions for using the equipment.

Wear gloves and use tongs when handling the cans with hotwater in them.

For You To Do

In this activity, put hot water into two aluminum cans, one unpainted and the other painted black.Use the Temperature Sensors to measure the temperature of the water in each can as it cools. Use

DataStudio or ScienceWorkshop to record and display the temperatures for each can.

Examine the plot of temperature versus time to find can transfers heat fastest.

PART I: Computer Setup

1. Connect the interface to the computer, turnon the interface, and turn on the computer.

2. Connect one Temperature Sensor toAnalog Channel A. Connect the secondTemperature Sensor to Analog Channel Bon the interface box.

3. Open the document titled as shown:

DataStudio ScienceWorkshop (Mac) ScienceWorkshop (Win)P46 Heat Transfer.DS P38 Heat Transfer P38_HEAT.SWS

The DataStudio document has a Workbook display. Read the instructions in theWorkbook.

The ScienceWorkshop document will open with a Graph display showing plots of Temperature vs. Time for each Temperature Sensor.

Data recording is set so there is one measurement each 10 seconds. Data recording stopsautomatically at 900 seconds (15 minutes).

p. 102 1999 PASCO scientific TP46


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Teachers Guide Physics Labs with Computers, Vol. 2012-06101C P46: Heat Transfer

PART II: Sensor Calibration and Equipment Setup

You do not need to calibrate the Temperature Sensors.

1. Prepare the two aluminum cans(one unpainted and one painted

black). Heat approximately 800milliliters of water to 90 C, but

dont fill the cans with water yet.Place each can on an insulated pad.Keep the cans away from drafts.

2. Fill each can to the same level withhot (90 C) water (approximately200 ml). Put Temperature Sensor Ainto the unpainted can and Temperature Sensor B into the black can.

PART III: Data Recording

1. When you are ready, start recording data. Data points will begin to appear in the graphevery 10 seconds.

2. Swirl the water in the cans continuously for 15 minutes. Data collecting will stopautomatically at 15 minutes.

Analyzing the Data

1. Set up your Graph to show statistics.

In DataStudio , click the Statistics menu

button ( ). Check thatMinimum and Maximum are

selected.In ScienceWorkshop , click the Statistics

button ( ) to open the statisticsarea on the right side of the Graph.Click the Statistics Menu button (

) and select Minimum andMaximum.

2. Record the maximum y value as theMaximum temperature. Record the

minimum y value as the Minimum temperature.

Record your results in the Lab Report section.

TP46 1999 PASCO scientific p. 103

ALUMINUM CAN,UNPAINTED

ALUMINUM CAN,BLACK

TEMPERATURESENSORS

TOINTERFACE

TOINTERFACE


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Physics Labs with Computers, Vol. 2 Teachers GuideP46: Heat Transfer 012-06101C

p. 104 1999 PASCO scientific TP46


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Lab Report - Activity P46: Heat TransferWhat Do You Think?

Parts of robot spacecraft are painted black while other parts are left unpainted. Part of the reasonis that unpainted sections of the spacecraft hull absorb energy more slowly than sections that arepainted black. Do you think the reverse is possible, will an unpainted aluminum can emit energyfaster or slower than a black colored aluminum can?

Answers will vary. For example, students may argue that the inside of the unpainted can willreflect energy back into the water.

Data Table

Can Maximum temperature Minimum temperature

Unpainted 84.0 C

68.4 C

Black 83.8 C

62.6 C

Questions

1. Which can cooled down faster?

Answers will vary. In the example above, the black painted can cooled down 21.2 C. The

unpainted can cooled down 15.6 C.

2. When the cans are cooling, which processes transfer heat? Which process do you think isdominant?

When the cans are cooling, conduction, convection, and radiation are all contributing to thetransfer of energy. The cans conduct some energy into the insulating pads they sit upon. Theylose some energy to the air through the openings at the top.

The dominant process is radiation.

3. When a can is cooling, does it cool faster at the beginning of the experiment or toward theend of the experiment? Why?

When a can is cooling, it cools down faster at the beginning of the cooling and less rapidly at theend of the cooling. The rate of cooling is directly proportional to the difference in temperaturebetween the can and its environment. As the cans temperature comes closer to the roomtemperature, the cooling rate drops.



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Time Estimates Preparation: 30 min Activity: 30 min

Objectives

Students will be able to use the Temperature Sensor to measure the change in temperature as two cans (one unpainted and

one colored black) with equal quantities of hot water emit energy use the Graph display determine the minimum and maximum temperatures as the two cans cool

compare the change in temperature of one can to the change in temperature of the other can

Notes

Encourage your students to be very careful when handling the hot water. Remind them to weargloves and to use tongs to handle the containers of hot water.

Stirring or swirling the cans continuously for fifteen minutes is very important. Also, it isimportant to stir or swirl the cans consistently.

Note: DataStudio and ScienceWorkshop results were obtained during separate data runs and can not be compared to each other.

DataStudio Sample Data



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tp46 heat transfer

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