Cricket-Match-Special ... A forum for discussion

backfootpunch wrote:And looking closely at the ball after pitching it is rotating end over end so cant possibly curve like drs is suggesting

I have it almost a ball width off of the true path, still out but not plumb in front

In short, yes it can, because the seaming ball is not the only thing that is subject to the Magnus effect, the front and back of the ball depending on spin will create different patterns of drag and accelerations. Top spin for instance will accelerate at the front of the ball quicker. You have to think that spinners routinely get the ball to do things in the air, like drifting it in or airing it, these are just natural expectations with certain types of swing. So a top spinner will drop on average much shorter than a normal ball, a sidespinner will drift in the air to the side away from the spin, and a backspinner will travel further in the air.

More importantly for this example, different combinations of spin produce varying results. I cant remember the exact combo that causes this kind of curving path, its either lots of topspin v a hint of side (corkscrew spin as they call it in Table tennis) or visa versa. I remember reading a group of Aussie scientists had test this a while back and found that if you could spin the ball in that way, you would get the spinning ball to move in the air like a swing ball, but from the spinners hand its nigh on impossible to impart this sort of curve in a legal delivery, however if you get a side spinning ball hit the ground and then change its spin direction while still maintaining some of its side spin, it can and will occur.

Seem to remember Steve Smith got out to a ball like this a few years ago. It pitched a long way down, and almost swung into him of the deck, as the spin wasnt just moving straight. At the time the commentators were a bit shocked and at first blamed hawkeye, but it was a long way from pitch to pad, so it wasnt a prediction, it was an accurate ball path judgement.

Hawkeye makes spin calculations because its an essential part of ball tracking in tennis, so is adequately set up to judge these spinning arcs.

It didn't move in the air at all between pitching and impact yet we are supposed to believe it swerves a ball width in such a small distance after impact

I'd be pretty dubious about that myself

It's a question of science. Lift coefficient is related to velocity, which means as a ball slows the spinning force governing it's direction increases, meaning balls move far more under deceleration. If you knew the pace and spin factors you could, like Hawkeye does, guess the path the spin takes the ball.

If you find it hard to believe, just look at a ten pin bowling ball. Professionals spin those balls to hook, but they go straight as a die for 85 percent of the lane before the friction force goes to a level that allows the ball to sharply, and very quickly over a short distance, jerk off at a different angle. You'd expect the ball to gradually spin that way, but it doesnt

In fact due to the Magnus effect the ten pin bowling ball initially fades slightly the other way, as the force of air it displaces acts contrary to it's spin direction