Bac STI2D - independent subject practice key terms

The chosen separation between a modeled system and its surroundings, determining which flows and interactions count as inputs or outputs.

A stated simplification or condition used to make reasoning possible, which limits where the result can legitimately be applied.

Agreement of physical dimensions across an equation, a necessary check that does not alone establish the correctness of its model.

A declared rule assigning positive directions or senses, required for consistent forces, moments, voltages, currents and coordinate calculations.

A representation of an isolated body with its external interactions, used to formulate the relevant equilibrium or motion equations.

A functional representation of connections or relationships that need not reproduce the physical layout, scale or operating authorization of equipment.

A specified allowable range or deviation for a characteristic, distinguished from measurement uncertainty and from statistical process control limits.

The smallest distinguishable display increment or input change under the device’s specified convention, which is not itself an accuracy guarantee.

An established relationship between instrument indications and reference values under stated conditions, with associated uncertainty and traceability.

The closeness of repeated results under specified similar conditions, which does not by itself demonstrate freedom from systematic bias.

The ratio of a change in indicated output to a change in measured input, with units and an applicable operating range.

A quantified or described limitation in knowledge of a measurement or prediction, arising from instruments, observations, parameters or model assumptions.

Checking whether an output or design meets specified requirements through appropriate analysis, inspection, measurement or testing evidence.

Assessing whether a model or solution is suitable for its intended use, which is different from merely matching its own specification.

A process identifying the authorized current version of drawings and records so changes remain traceable and incompatible versions are not mixed.

The defined service or output used as the basis of a comparison, particularly important when evaluating lifecycle or resource burdens.

A ratio of specified useful output to corresponding input over a consistent system boundary, distinct from heat-pump coefficient of performance.

The rate of energy transfer or work, measured in watts in SI, rather than an accumulated amount of energy.

A quantity transferred or stored through physical processes, measured in joules or compatible units such as kilowatt-hours with explicit conversion.

The route by which actions are transmitted through members and connections to supports, including relevant intermediate construction conditions.

Force divided by an explicitly defined reference area, commonly original cross-sectional area in a basic tensile-test convention.

Change in length divided by the stated original length, a dimensionless measure whose percentage form must be converted before some calculations.

Resistance to deformation for a material or component under a stated relationship, distinguished from strength and affected by geometry at component level.

Resistance to a specified failure or yielding criterion under given conditions, which cannot be inferred from stiffness alone.

A situation in which improving one design criterion can worsen another, requiring explicit priorities rather than a claim of universal superiority.

The ability to follow a result or item through identified records and references, supporting checks of origin, conditions and revision history.

A root-mean-square measure of a varying quantity; its relation to a peak value depends on waveform rather than a universal square-root-two conversion.

Use of information about an output or state to influence a control action, distinguished from monitoring that does not change the command.

A model-based comparison of a stable process distribution with specification limits, requiring suitable variation estimates and a stated acceptance criterion.

The value of the next-best alternative forgone when allocating limited resources, which matters even when a project has no immediate purchase price.