Someone argues: "My vernier calliper is traceable to the SI metre
PHYSICS · Subjective · Fermi University Physics · Scientific Practice & Experimental Methods · Quantities, units and the practice of measurement · Quantities, units and the practice of measurement
Measurement and Method, Ch The instrument: resolution, sensitivity, calibration and traceability
Problem
Someone argues: "My vernier calliper is traceable to the SI metre. I checked it against a steel ball bearing whose catalogue page states a diameter of 12.700mm, and my calliper agreed to within 0.02mm. Since the catalogue value is a length in millimetres, and the millimetre is an SI unit, my calliper is traceable back to the defining constants." Find the broken link in this reasoning, and state what the catalogue page would need to show for the chain to be genuine.