<P> In 1901, the 3rd General Conference on Weights and Measures (CGPM) established this as their official definition of weight: </P> <P> "The word weight denotes a quantity of the same nature as a force: the weight of a body is the product of its mass and the acceleration due to gravity ." </P> <P> This resolution defines weight as a vector, since force is a vector quantity . However, some textbooks also take weight to be a scalar by defining: </P> <P> "The weight W of a body is equal to the magnitude F of the gravitational force on the body ." </P>

The weight of a substance is defined as