PHY.5:1 - Problem frame

Use this pattern when a physical question leaves you uncertain which motions, interactions or material details its description must retain. Resolving every microscopic change may be impractical. Omitting a fast motion or a small interaction may change the answer that matters.

Begin with one consequence: a response over a stated interval, a propagation speed, an accumulated exchange, or a distribution of outcomes. Choose one proposed omission and follow how it could affect that consequence. A simpler account with a justified range of use, or a reason to restore the omitted contribution, is a useful first result.

An effective physical description here describes the physical behavior needed at chosen scales without resolving every underlying process. Unresolved processes can still contribute through response coefficients, constraints, dependence on earlier states or fluctuations. The method helps choose and examine that description across physical branches.

You need to identify the physical participants, explain the interactions relevant to the question and compare their characteristic sizes or rates. A qualitative separation can direct the next construction. The examples add their own mathematical preparation: elementary differential equations for the motor, waves for the discrete chain, and covariance for thermal motion.

When a known physical account already answers the question under the intended conditions, use it. PHY.1 supplies similarity between changed arrangements; PHY.2 constructs an analogue from physical interactions. MMP.9 supplies mathematical reduction once the governing relations and retained quantities have been chosen. Use this pattern for the physical choice of those quantities, relations and conditions.