 Newton called momentum the “quantity of motion,” which is an apt label, because, very roughly, it is a measure of the extent to which an object is moving relative to an inertial reference frame. Our colloquial use of the word “momentum” is related to this intuition and to its formal definition as the product of the mass of an object times its velocity relative to some inertial reference frame. If object \(B_2\) has twice the mass as \(B_1\) but moves with the same velocity relative to a reference frame, \(B_2\) has twice the momentum. 