Thus, in the case of the bubble motion the Magnus force is determined from empirical relationships [6, 8].
It is a result of big turbulences of the liquid while dividing near the bubble, the Magnus force is generated and its direction changes very fast.
Air motion in big bubbles causes reduction of the Magnus force, so big bubbles in free motion move with much less oscillations than small bubbles.
Since the Magnus force depends on the angle between the spin axis and the trajectory, and this angle is zero in the gyroball, the net Magnus force on the ball is zero.
As there is no Magnus force acting on the gyroball, the exaggerated break reported in a number of publications is false.
First, the gyroball has no Magnus force to lift it against gravity (as does a fastball) or to augment the pull of gravity (as does a curveball).
The figure is a scatterplot showing the vertical break versus the horizontal break, where "break" is defined to be the deviation from the trajectory due to the Magnus force.
The Magnus force - named after H G Magnus, a German physicist who first investigated its properties about 150 years ago - is directly responsible for curling the ball off its normal path.
According to Mr Matthews, the real skill comes in controlling the third force, aerodynamic drag, which changes with the speed of the ball but which can also affect the Magnus Force.
Struck off-centre and hard, the ball starts off flying wide of the wall but as the ball slows, the drag increases rapidly, boosting the Magnus Force, making the ball curl ever more swiftly into the back of the net,' he said.
The Magnus force
and deflection of the pitch are reduced because the hand rolling over the ball produces a slow spin with the axis shifted toward the direction in which the ball is moving.