Temperature and Heat -- Thermal Equilibrium

Exploring Thermal Equilibrium: Is water cold? Is wool warm?

Here is an exploration that will help you start thinking about thermal equilibrium.

Materials: thermometers*, two glass jars with lids (big enough to hold a thermometer) or a can and a sealable bag of water, a woolly sock or a glove.

Compare the thermometers in your kit to each other. Put them on your work surface and allow their temperatures to stabilize, and then note the temperature of each one before you do the following investigation. They should agree, but there may be some variation (of perhaps a degree) because these thermometers are not very accurate devices.

We found out in the first section that the bulb is the sensitive part of the thermometer. So be careful not to touch the bulb: you want to measure the temperature of the things that are part of your experiments, not your temperature! We'll always be interested in how much each thermometer changes relative to where it started.

Prepare several thermometers as follows:

Record the starting temperature of all of your thermometers
Put one thermometer in a woolly sock or a fur-lined mitten -- something you would want on a really cold day.
Put one thermometer in a jar or plastic bag of water, sealed up tight or covered with plastic wrap.
Put one thermometer in a clean dry glass jar or metal can.
Wrap one thermometer in aluminum foil
And put one thermometer however you think would best measure the temperature of the air in your experiment -- lying on a dry paper towel? Hanging just above the table top? You decide.

Leave the thermometers someplace with as constant an environment as possible (away from heating vents, sunlight, and doors, and where they will not be disturbed) for at least 3 hours. We are trying to determine the effect of the different treatments of the thermometers, and want everything else to be the same.

Write down now your predictions: what will happen to the temperatures of the thermometers in each of the different environments?

Three or more hours later:
Without handling the thermometers or containers, read the final temperature in each system, and compare them to each other and your predictions.

Now touch each container and decide whether it feels warmer or cooler than the others. Does your temperature-sense agree with the thermometer?

Write something in your notebook on what you learned: does wool make the thermometer warm? Is water cooler than the air? How do the temperatures compare with what you predicted? Are the differences in temperature that you see significant and reproducible? You might also discuss precautions that need to be taken to make a really good test.

Please remember that we will want to see your notebooks at the end of the workshop.

Check the box when you are done: Next activity: Equilibration

There is a similar classroom activity "Room Temperature #1" in the teacher manual.