The Libori Summer School “Émilie Du Châtelet: Matter, Bodies, Forces, Motion” focuses on some of the chapters from Du Châtelet’s Institutions de physique (1740/42) within the context of the scientific thinking of her time.
In the early 18th century, the Dutch physicist Willem Jacob 's Gravesande, at Leiden University, performed a number of experiments wherein he dropped balls of different mass on soft clay, finding that if the heights from which the balls fell were inversely proportional to their masses, the indentations made by the balls would be the same. He concluded that the measure of the force of the impact on the clay is given by the weight times the velocity squared and that, in the case under consideration, equal forces are produced if the velocities squared are inversely as the masses. Gravesande communicated his results on the impact of falling weights to Émilie du Châtelet. In her Institutions de physique (1740/42), du Châtelet combined the practical observations of Gravesande to the Leibnizian idea of living forces in order to show that the energy of a moving object is proportional to the square of its velocity: “Maintenant, enfin, il y avait une justification forte pour considérer mv2 comme une définition féconde de l'énergie.”