The objective today is for you to see the power of the ocean to stabilize our planet's temperature. We will accomplish this by comparing the thermal mass and ability to absorb heat of to types of materials, sand and water.

Solar energy, or energy from the sun, is one energy alternative. A passive solar heating system uses no pumps, fans, or mechanical devices. Insulation and heat storage are important factors in such a system. Heat can be stored using thermal masses, also called "heat sinks." Thermal masses can keep a home from heating or cooling too fast. In this experiment, you will examine the effectiveness of a thermal mass. Later in the year , you will then use what you learn in this experiment and experiment 14 isolation angle to design and build a model solar home.

OBJECTIVES

In this experiment, you will

• use a computer to measure temperature

• graph temperature data

• determine the relationship between thermal mass and the ability of a material such as water or sand to retain heat

 

MATERIALS

Macintosh or IBM-compatible computer	empty container
Serial Box Interface or ULI	room-temperature water
Logger Pro	lamp with 100-watt bulb or sunny location outside.
2 Vernier Temperature Probes	Water in a matching bucket or container
sand in one bucket or container

 PROCEDURE

 

 

1. Fill two buckets, one with sand the other with water. These are the thermal masses, the material that stores and retains heat. Position them 20 cm apart facing the bulb as shown above. Or position them facing the sun if working outside.

2. Fill a bottle with room-temperature water. This will be the thermal mass, a material that absorbs and stores heat, for Part I. Firmly tighten the bottle cap and lay the filled bottle inside one of the model solar homes. Leave the other model home empty. Tape both model homes shut.

3. Position a lamp to shine down between the buckets as shown in Figure 1. The lamp bulb should be 10 cm above the table top and equidistant from the containers. Do not turn the lamp on yet.

4. Position Probe 1 in the container with no thermal mass ( empty) and Probe 2 in the bucket with the thermal mass. In both cases, pass 1/2 of the probe through the hole provided and make sure the probe is not in direct light from the lamp.

5. Prepare the computer for data collection by opening "Exp 15" from the Physical Science with Computers experiment files of Logger Pro. The vertical axis will have temperature scaled from 20 to 60°C. The horizontal axis will have time scaled from 0 to 80 minutes.

6. You will be collecting data for 80 continuous minutes. During the first 40 minutes, the light will be on. After 40 minutes have passed, the light will be turned off and the tops of the containers will be covered. "Not lighted" data will be collected for 40 more minutes.

7. Click to start data collection. Turn the light on after the first set of temperature readings appears on the screen.

8. After 40 minutes, turn the light off and cover the tops of the containers with a piece of cardboard. Data collection will end when a total of 80 minutes has passed.

9. Determine the maximum temperature reached in each of the containers:

 • Click the Examine button, .

• Move the mouse pointer to the highest point on Curve 1.

• The temperature at this point is displayed. Record this Probe 1 (no thermal mass) maximum temperature.

• Move the mouse pointer to the highest point on Curve 2.

• Record the Probe 2 (with thermal mass) maximum temperature.

10. Move the mouse pointer to the 80-minute line. Record the two temperatures at 80 minutes.

11. Print copies of the graph as directed by your teacher.

12. repeat the procedure using a different thermal mass, ie sand if you used water the first time.

DATA AND CALCULATIONS

Probe 1 / No thermal mass	2 / With thermal mass - sand
Maximum temperature _____°C	Maximum temperature _____°C
Temperature at 80 minutes _____°C	Temperature at 80 minutes _____°C
Maximum temperature minus temperature at 80 minutes _____°C	Maximum temperature minus temperature at 80 minutes _____°C
trial #2
Probe 1 / No thermal mass	2 / With thermal mass - water
Maximum temperature _____°C	Maximum temperature _____°C
Temperature at 80 minutes _____°C	Temperature at 80 minutes _____°C
Maximum temperature minus temperature at 80 minutes _____°C	Maximum temperature minus temperature at 80 minutes _____°C

 PROCESSING THE DATA

 1. Subtract to find the temperature drop for each container as it cooled from its maximum temperature to its temperature at 80 minutes (maximum temperature &emdash; temperature at 80 minutes). Record the differences in the Data and Calculations Table above. Which container cooled more?

 

 

 

 

 

 

2. How are the "no thermal mass" and the "with thermal mass" curves similar? How are they different?

 

 

 

 

 

3. Which container heated more slowly?

 

 

4. Which container cooled more slowly?

 

 

 

 

 

5. What effect does the thermal mass have on the heating and cooling of a container ?

 

 

 

 

 

6. Is it best for thermal mass to have a high or low specific heat? Explain

 

EXTENSIONS choose one to do

1. Run the experiment for two or more consecutive "daily" cycles of four hours or longer.

2. Design an experiment to test other types of thermal mass, such as stones or phase-change materials.

3. Design an experiment to test other variables affecting a heat , such as color, plant life or salinity.

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