Force meter
A force meter is an instrument to measure the magnitude of a force. This is often just a spring contained within a cylinder that has a scale to mark the extension of the spring produced by the force. In the International System of Units, the unit of force is the newton (symbol N). A force meter that measures force in newtons may be referred to as a newtonmeter.
Physical constant
On November 16, 2018, the International Bureau of Weights and Measures voted to redefine several base units in the International System of Units (SI) by fixing the SI value of several physical constants, including the Planck constant, "h", elementary charge, "e", Boltzmann constant, "k", Avogadro constant, "N", and the speed of light, "c". The new fixed values are based on the best measurements of the constants based on the earlier definitions, including the kilogram, to ensure minimal impact.