Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies. — The basic SI unit of mass is the kilogram …
Cast iron weight used for balances – Weight: 2 kg (4.44 lb) Height: 4.9 cm (1.9 in); Width: 9.2 cm (3.6 in).
Galileo Galilei (1636)
Distance traveled by a freely falling ball is proportional to the square of the elapsed time