Energy Transferred by Working
Energy and Thermal Physics
A quantitative introduction
Physics Narrative
for 11-14
Energy is quantitative
Energy is quantitative in essence: if you are not using the idea of energy to make quantitative comparisons, then you're likely abusing the idea. The quantity of energy places a limitation on possible changes, it does not cause any of those changes.
As quantifying energy requires you to freeze the action, so looking from snapshot to snapshot, power, which enables you to analyse what is happening now, is often more useful. The accumulation of power over the duration of a process is the energy that is shifted over that process.
