  The Giornata Sesta about the Force of Percussion is a relatively less known
Chapter from the Galileo's masterpiece "Discourse about Two New Sciences". It
was first published lately (1718), long after the first edition of the Two New
Sciences (1638) and Galileo's death (1642). The Giornata Sesta focuses on how
to quantify the percussion force caused by a body in movement, and describes a
very interesting experiment known as "the two-bucket experiment". In this
paper, we review this experiment reported by Galileo, develop a steady-state
theoretical model, and solve its transient form numerically; additionally, we
report the results from one real simplified analogous experiment. Finally, we
discuss the conclusions drawn by Galileo -- correct, despite a probably
unnoticeable imbalance --, showing that he did not report the thrust force
component in his setup -- which would be fundamental for the correct
calculation of the percussion force.

History and Philosophy of Physics