Originally Posted by grity
the main difference between falling in air and in water is the specific weight of the medium
Just to keep it simple, in water as in air, three forces and their moments are at play on a free-falling body: Weight, buoyancy and fluid dynamic force. Buoyancy is equal to the weight of the displaced volume of the medium, usually negligible in air but not in water. The fluid dynamic force is equal to fluid density times velocity-squared times a factor that depends on the geometry of the moving body: dimensions, shape and orientation relative to the direction of movement.