Despite limited tools, Leonardo da Vinci displayed ingenious problem-solving. The authors examine a combination of Leonardo’s thought and physical experiments regarding the acceleration of falling objects. Leonardo recorded that if a water-pouring vase moves transversally (sideways), mimicking the trajectory of a vertically falling object, it generates a right (as in orthogonal) triangle with equal leg length, composed of falling material lining up diagonally (forming the hypotenuse) and the vase trajectory forming one of the legs. On the hypotenuse, Leonardo wrote “ Equatione di Moti ,” or equalization of motions, noting the equivalence of the two orthogonal motions, one effected by gravity and the other prescribed by the experimenter. The authors present an analytical solution using Newtonian mechanics to confirm Leonardo’s “Equivalence principle.”