The kilogram and measurements of mass and force

Abstract

This paper describes the facilities, measurement capabilities, and ongoing research activities in the areas of mass and force at the National Institute of Standards and Technology (NIST). The first section of the paper is devoted to mass metrology and starts with a brief historical perspective on the developments that led to the current definition of the kilogram. An overview of mass measurement procedures is given with a brief discussion of current research on alternative materials for mass standards and surface profiles of the U.S. national prototype kilograms. A brief outlook into the future possible redefinition of the unit of mass based on fundamental principles is included. The second part of this paper focuses on the unit of force and describes the realization of the unit, measurement procedures, uncertainty in the realized force, facilities, and current efforts aimed at the realization of small forces.

Study of the friction, adhesion and mechanical properties of single crystals, ceramics and ceramic coatings by AFM

“…In principle, smaller masses could be calibrated, but they would be difficult to handle. 111 Moreover, the relative uncertainty tends to increase inversely with mass, 111 potentially resulting in uncertainties that are of similar magnitude to deadweight forces in the range of nanonewtons. Besides, forces in this range can be measured using the electrical units defined in the International System of Units (SI) and linked to the Josephson and quantized Hall effects in combination with the SI unit of length.…”

Metrologies for quantitative nanomechanical testing and quality control in semiconductor manufacturing

“…5 µ N) with a relative standard uncertainty of a few parts in 10 4 . In principle smaller masses could be calibrated by NIST, but they would be difficult to handle, and the trend is for the relative uncertainty to increase in inverse proportion to the decrease in mass 26 . Extrapolating from this trend, the uncertainty could very well be as large as the force for a deadweight producing 1 nN.…”

On the indeterminacy of the meter

“…objection is that I agree that the SI system has a dramatic indeterminacy because of the conventional definition of 'kilogram'. However, the Bureau International des Poids et Mesures (BIPM), which is the international 33 Jabbour and Yaniv (2001). 34 See Eklund (2011) for example.…”