some more Magnus ……. !


The Magnus effect can be applied in any direction, and in this way an athlete can create backspin, topspin, and sidespin. Soccer players are well known for the way they use “banana kicks” (i.e., the Magnus effect) to curve free kicks and corner kicks around defenders and into the goal mouth Tennis players and volleyball players use the Magnus effect when they apply topspin to make the ball drop suddenly while in flight. Elite golfers apply Magnus forces to produce draws and fades, and the weekend hacker unwittingly applies spin and uses the Magnus effect to slice the ball off to the left and right.

The Magnus effect can combine with the force of gravity or fight against gravity. Topspin combines with gravity’s downward pull, and this is why topspin forehands in tennis (and table tennis) arc viciously over the net and down toward the court. Topspin rotates in the same direction that the ball is traveling, and the spin causes the ball to accelerate once it hits the playing surface.

Backspin, on the other hand, fights against gravity. The more backwards spin, the more the ball will “hang” in the air. Because the backspin is rotating in the opposing direction that the ball is traveling, the spin causes the ball to slow down and even jump backward once it hits the playing surface. Experienced tennis players are able to “read” the spin on the ball from the motion of their opponent’s racket.

Spin bowlers use the magnus effect, perhaps sometimes unknowingly, to create drift & turn. They do it by imparting revolutions onto the ball; the more revolutions the bowler can make the ball do in flight, will directly affect  how much drift (and consequently turn once the revolving ball hits the pitch) is achieved. So it basically boils down to making the ball rotate in the air. The more efficiently the ball rotates, the better. Also, the ball will behave differently depending how the seam is presented; i.e. if the ball is spun across seam, as opposed to down seam, it will cause a difference in the air pressure waves.

So the next time you analyse a spin bowler; remember what is actually important ! You need to focus on how efficiently they get the ball to rotate (around its axis) on its way down to the batter, because the increased rotations means that Magnus effect will make it move in the air, in the direction of the spiral and the rotating ball will kick off the pitch better (hopefully !)

This begs one very important question though . . .
If the science of bowling spin means that the bowler uses Magnus effect to get lateral dropping movement, then the knock on effect is the ball deviates off the pitch (spin); thus creating two seperate problems for the batter to negotiate. . .
Why do we here loud complaints about spinning or non spinning pitches ?
Because surely, well over 50% of the spinning effectivity is actually generated before the ball even touches the floor !

Maybe, as might be the case with swing bowling, the bowler psychologically does not “Rip” it as much if he thinks the pitch is not going to spin, thus entering a catch 22 situation as you wont get one without the other.

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