Fruitful energy descriptions

Provide a context to establish purpose, setting up energy descriptions. The context supports the identification of physical variables, enabling energy descriptions and calculations. The insight derived from from the description or calculation will relate back to the context.

#### A teaching schema

Here are four elaborated schema, in two pairs, which could reliably guide the construction of purposeful energy descriptions.

Compare energy

• possibilities
• efficiency
• Equate energy

• physical quantities
• Compare one calculated energy change with another calculated energy change, enabling a discussion of whether the process that corresponds to those changes is possible or not(simple example: whether a roller coaster travelling at a particular speed could crest a hill).

#### Compare schema: possibility

Compare one calculated energy change with another calculated energy change, enabling a discussion of the efficiency of the process corresponding to those changes (simple example: what percentage of the energy in the chemical store ends up shifted to the energy in the gravitational store of a combustion motor powered lift).

#### Compare schema: efficiency

Equate two changes in energy, one of which is probably calculated, but now use these values to calculate a physical quantity–typically the maximum possible value of that quantity, so assuming no dissipation(simple example: find the expected top speed of a cyclist freewheeling down a particular hill).

#### Equate schema: physical quantity

Equate two changes in energy, both of which are probably calculated, but vary the compensated quantities for one calculation, usually assuming no dissipation(simple example: the range forces and distances that could be used to lift a load using varying levers).