Previously you learned about an additional form of energy associated with an object, thermal energy.

When the temperature of an object increases, its thermal energy increases.

When the temperature of an object deceases, its thermal energy decreases.

One way the thermal energy of objects can change is when they are in contact and rubbing against each other; for example, when a block slides on a table, or when a soccer ball slows down as it slides along the grass.

You also learned about how to evaluate a scientific explanation regarding a natural phenomenon in terms of its accuracy (based on evidence and consistent with ideas developed in class). The explanation usually consists of a diagram (e.g., an energy diagram) and a written narrative. A good written narrative usually begins with a description of the interaction(s) involved and is followed by statements about the various energy transfers and changes. The statements should be in a logical order that makes it easy to understand the explanation. The last sentence should connect some energy change to the situation being explained.

The purpose of this homework is to give you the opportunity to practice constructing some explanations and evaluating others for their accuracy.