Calculating power and energy
Physics Narrative
for 11-14
Power is about what's happening; energy is about what has happened or might happen
Simple calculations can find the energy shifted to or from a store between one time and another (from snapshot to snapshot). So these quantities are about complete processes: either analysing a process that has occurred, or about determining whether a potential process can or cannot happen. A natural way to represent these accumulations (whether positive or negative) is in terms of a bar.
The power in a pathway is a measure for a process that is incomplete: it is still happening when the measure is valid. A natural way to represent these accumulations (whether positive or negative) is in terms of a Sankey arrow, as these are essentially about flow.
