A balance gives the same reading anywhere
#0019 Science & nature
Fact rank
A
An industry handbook and a technical paper by a scale maker's engineer agree; that beam-type body scales exist was confirmed in a maker's catalogue
Wow rank
B
Mildly surprising that an "electronic balance" is not really a balance
Usefulness
B
A small advantage when buying a scale or moving house
Verification: Supported by evidence
Rule check: an article whose "why" cannot be written with sources is capped at fact rank B.
AI verification reports the evidence it found; it does not guarantee that a claim is true.
A balance that weighs against reference weights gives the same reading anywhere, because gravity acts equally on both sides and cancels out. An electronic balance, despite its name, measures force, so its reading changes from place to place and it is calibrated where it is used.
Why
(No sourced explanation yet.)Evidence
Secondary Sample chapter of a scale handbook (Nikkan Kogyo Shimbun). Balances and steelyards compare the gravity acting at the same time on the weights and on the object; spring scales measure gravity directly. An electronic scale reading 1.0000 kg in Tokyo reads 0.9996 kg in Kagoshima and 1.0007 kg in Sapporo link
Primary Explanation by an engineer at a scale maker (A&D, 2020). An electronic balance measures the gravity on the sample as mass, so its display changes when gravitational acceleration changes; high-resolution electronic balances are calibrated on site link
Primary Catalogue of a US maker of medical scales: a mechanical beam scale with height rod (up to 180 kg), weighed by sliding poises along a beam link
Notes and limits
A balance is still affected by differences in air buoyancy, so the precise statement is that it is unaffected by local differences in gravity. Beam-type medical scales are still sold abroad, but scales in Japanese homes are almost all electronic. That a balance is unaffected by gravity is also in the Japanese Wikipedia article on balances.
Derivations
Derived from: 体重計の数字は緯度が高いほど大きく出る
Derived facts: —