Abstract
HAVING read with much interest Prof. Greenhill's letter in NATURE of March 24, p. 486, I am inclined to think that much of the perplexity felt by some who begin the study of dynamics arises from the want of names for the units of the various magnitudes with which the science deals. We have names for units of time, space, mass, force, work; but no names for units of velocity, acceleration, impulse, momentum, &c. I venture to suggest the following:—Let the unit velocity be that with which a point describes uniformly one foot per second. Let this unit be called a cel. Let the unit acceleration be that whereby the velocity is uniformly changed by one vel per second. Let this unit be called a cel. Then everything becomes clear. E.g. the meaning of the equation W = mg is seen to be this: The weight of a mass of m pounds at a place where the acceleration arising from the mutual stress between it and the mass of the earth is g cels being W poundals, the numbers W mg are connected by the equation W = mg. Then, for the sake of the beginner, let the names of the units be given thus: W = mg poundals,m = W/g pounds, g= W/m cels. It is too common to see acceleration expressed in feet per second, instead of in vels per second. If the weight of a mass of m pounds be defined to be the mutual stress between it and the mass e pounds of the earth, it is evident that the weight of e attracted by m is the same as the weight of m attracted by e; and, in the absence of either, the other would have no weight.
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GEOGHEGAN, E. Units of Weight, Mass, and Force. Nature 35, 534 (1887). https://doi.org/10.1038/035534b0
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DOI: https://doi.org/10.1038/035534b0
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