Mensuration

Abstract

The word ‘mensuration’ means ‘measuring’ or ‘measurement’ and is the word normally applied to the branch of mathematics concerned with the determination of lengths, areas and volumes. These include not only the obviously required details of engineering components but also what appear at first sight to be ‘academic’ measurements of, for example, the area contained between part of a graph and the axes of the variables. In engineering such areas may be particularly important; for example the area beneath a voltage or current graph, which is proportional to the energy absorbed by the circuit, and the area of the magnetic hysteresis loop (a graph plotting flux density against magnetising force), which again is a measure of the energy required to carry out magnetising and demagnetising. The area beneath the graph of a variable quantity is also used to determine the average value or the equivalent constant value of that quantity — for example, with alternating current, to determine the value of the equivalent direct current (that is, the direct current which would deliver the same power to a circuit).