The gravity field in force standard machines

Abstract

The gravity acceleration g plays an important role in several physical quantities as provided by National Metrology Institutes. The unit of force is realized in dependence on g in force standard machines (FSM). We present the results of the combination of forward modeling and gravimetric observations to determine the absolute value of g inside the new 200 kN FSM of the Physikalisch-Technische Bundesanstalt (PTB). A model of the machine itself and gravimetric measurements, performed prior and after the installation of the FSM, are compared. The agreement is within 10 nm/s^-2. The final uncertainty concerning g is 1.2x10^−7 due to temporal variations typically neglected in force measurements.