Recoil = Cannon Ball / cannon x speed of cannon ball.
7.42 = 32.5/ cannon x 388
7.42 = 32.5 x 388 / cannon
7.42 = 12,610 /cannon
7.42 x cannon = 12610
Cannon = 12610/7.42
Cannon = 1699.46 kg. ( Round answer as needed)