A load receptor is the part of a weighing scale intended to receive the load, such as the platform supporting a parcel. The instrument can transmit that load's force to a separate measuring element, for example a load cell.[ref]
A simple static model explains why the physical support path matters. Suppose a object rests entirely on a horizontal load receptor, with local gravitational acceleration . Neglecting air buoyancy, its gravitational weight is . The instrument can convert the measured supporting force into a mass indication through its calibration.
Now arrange a separate overhead support to carry of the same object's gravitational weight, while the rest still reaches the load receptor. The scale then supports and, under the same ideal calibration, indicates . The object's mass remains : the indication changed because the support path changed. This is an illustrative static equilibrium experiment, rather than a claim about any instrument's specified error.
A removable container placed on the platform contributes tare mass; it is distinct from the instrument's own load receptor. To measure the net mass of the contents, the tare device changes the indicated reference while the receptor continues to carry both container and contents. Contact with an external support can therefore defeat an otherwise correct subtraction.
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