PHY.6:2 - Problem

A balance says how accumulation relates to transfer and production. It can leave the transfer itself unknown. Adding a convenient rate formula may complete an equation system while describing the wrong physical interaction.

Combining individually useful descriptions adds another difficulty. A contact may store a quantity, a connection may impose a constraint, and two parts may use different signs or reference frames. Initial values acceptable to each isolated part can be impossible after they are connected. A solver can then fail for a physical reason, or return a result for a preparation different from the intended one.

The task is to construct mutually compatible physical relations and preparation, then derive the consequence that the work needs.