Choosing how much to study

Building simple models

With any process, as well as identifying start and end points to the energy analysis, it is also worth thinking about the extent of what you choose to analyse.

For example, in relation to the lifting process, it is possible to focus purely on the lifting agent, and the ornament in the Earth's gravitational field. If you're lucky, you'll find that all of the energy shifted from the chemical store ends up in the gravitational store.

However it is more likely that this will not be the case and that you'll have to extend the boundaries of what you consider to include the surroundings. Here things become a little more complicated! Rather than assuming that all of the energy is shifted from chemical to gravitational stores, now we must investigate whether any energy goes to warming up the surroundings, thereby ending up in the thermal store of the surroundings.

If the amount of energy shifted to the thermal store of the surroundings is relatively small compared with that shifted to the gravitational store, a physicist might chose to ignore it and therefore model the process much more simply, thinking about only two stores, without too much error.