Thermal Energy vs. Temperature

Last updated almost 5 years ago

7 questions

Note from the author:

This Formative includes a video discussing the difference between temperature and thermal energy and then gives the students some practice questions.

Thermal Energy vs. Temperature
You might want to have a calculator handy for this lesson!

Watch the video below.

Let’s say we have some molecules of cold water with the given amounts of kinetic energy.

Find the total thermal energy of the cold water.

Now find the temperature of the cold water.

Now what if we mix the hot and cold water?

If we mix the hot and cold water molecules, the hot water molecules will __________ thermal/kinetic energy.

The cold water molecules will __________ thermal/kinetic energy.

When we mix the hot and cold water together, the molecules will transfer energy by conduction.  Suppose the thermal/kinetic energy of each molecule changes as indicated in the picture.

What is the total thermal energy of the mixed water?

What is the temperature of the mixed water?

One last point to ponder:
Remember, the temperature of the hot water was 42 degrees. The temperature of the cold water was 12 degrees. The halfway point between those two temperatures is 27 degrees. But the temperature of the mixed water is 24 degrees, which is not halfway in between, but a little closer to the cold water temperature than to the hot water temperature. Why do you think the mixed water temperature ended up a little bit below the halfway temperature?