Question: How do you have to swing a racket to spin the ball parallel to its trajectory?
About the article "Table tennis", section "Corkspin".

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This type of spin is almost exclusively employed in service, but it is also used from time to time in the lob at the professional level.
Unlike any of the aforementioned techniques, corkspin (sometimes referred to as "drill-spin") features a unique situation in which the axis of spin is more or less parallel to the trajectory of the ball.
This means that the Magnus effect will have little to no effect on the trajectory of a cork-spun ball.
Upon bouncing, the ball will dart right or left, depending on the direction of the spin, making it very difficult to return.
Although in theory this type of spin produces the most obnoxious effects, it is not as strategically practical as sidespin or backspin in terms of the limitations that it imposes upon the opponent during their return.
Aside from the initial direction change when bouncing, provided that it does not exceed the reach of the opponent, a cork-spun ball is easily countered with topspin "or" backspin.
Similar to a backspin stroke, the corkspin stroke has a lower maximum velocity, simply due to the contact angle of the racket when producing the stroke.
To impart a spin on the ball which is parallel to its trajectory, the racket must be swung more or less perpendicular to the trajectory of the ball.
This greatly limits the amount of forward momentum that can be transferred to the ball by the racket.
Corkspin is almost always mixed with another variety of spin, as it is less effective and harder to produce on its own.
Swing bowling.
To do this a curved piece of tubing is attached to the end of the barrel.
The ball rolls around this causing it to spin and swing. 
A major element of strategy in these sports is the condition of the ball.
Since bowling in cricket has more variations (such as bounce, swing, seam movement, off-spin, leg-spin and so on), the condition of the ball also affects play to a great degree.
In Test cricket, the same ball must be used for at least 80 overs unless it is lost, damaged or illegally modified and then it must be replaced with a ball of a similar condition, after which, obtaining a new ball is at the discretion of the fielding captain whereas, in baseball the ball is replaced numerous times during a game to ensure it is in optimum condition.
Often, the fielding captain might opt for the new ball straightaway, since a new ball is harder, bounces higher and has an intact seam, which produces greater conventional swing.
But when a captain feels that a spin bowling attack is more likely to be successful, he will persist with the old ball, which is rougher and better grips the surface as well the bowler's fingers.
The aerodynamics of swing in cricket are different from baseball.
Moreover, the raised seam also causes movement off the pitch in cricket, which is a very important part of medium pace bowling.
Once a particular hemisphere of the cricket ball is more rough or scratched than the other, the fielding team meticulously works to preserve the shine on the other half by rubbing it on their clothes or by applying saliva (no "external" substances can be applied to alter the condition of the ball).
Bowlers very carefully regulate their wrist position at the point of release to ensure the shine is preserved only on one half of the ball, since it will swing towards the rough side.
The old ball in cricket also tends to generate greater amounts of reverse swing, which is swing towards the polished side.
This can be exploited by a captain with genuinely fast bowlers (usually, those who can bowl over ) at his disposal.
Especially on pitches in the Indian sub-continent, which tend to have abrasive surfaces, bowlers might resort to bowling across the seam as early as the tenth over, so as to quickly scruff up the ball and generate reverse swing early on.
Strategies that rely on early reverse swing also need the backup of effective spin bowlers to be able to exploit the roughed up ball.
Due to these factors, a batsman in cricket needs to very carefully watch how the bowler grips the ball even during his run-up, as well as the type of revolutions on the ball as it approaches.
Master spin bowlers like Shane Warne & Muttiah Muralitharan, who were able to dramatically vary the trajectory, direction and extent of spin, regularly bowled deliveries with a scrambled seam to disguise the type of ball actually bowled. 
The Magnus effect explains commonly observed deviations from the typical trajectories or paths of spinning balls in sport, notably association football (soccer), table tennis, tennis, volleyball, golf, baseball, cricket and in paintball marker balls.
The curved path of a golf ball known as "slice" or "hook" is due largely to the ball's spinning motion (about its vertical axis) and the Magnus effect, causing a horizontal force that moves the ball from a straight-line in its trajectory.
Back-spin (upper surface rotating backwards from the direction of movement) on a golf ball causes a vertical force that counteracts the force of gravity slightly, and enables the ball to remain airborne a little longer than it would were the ball not spinning: this allows the ball to travel farther than a non-spinning (about its horizontal axis) ball.
In table tennis, the Magnus effect is easily observed, because of the small mass and low density of the ball.
An experienced player can place a wide variety of spins on the ball.
Table tennis rackets usually have a surface made of rubber to give the racket maximum grip on the ball, to impart a spin.
The Magnus effect is not responsible for the movement of the cricket ball seen in swing bowling, although it does contribute to the motion known as "drift" in spin bowling.
In airsoft, a system known as Hop-Up is used to create a backspin on a fired BB, which will greatly increase its range, using the Magnus effect in a similar manner as in golf.
In paintball, Tippmann's Flatline Barrel System also takes advantage of the Magnus effect by imparting a backspin on the paintballs, which increases their effective range by counteracting gravity.
In baseball, pitchers often impart different spins on the ball, causing it to curve in the desired direction due to the Magnus effect.
The PITCHf/x system measures the change in trajectory caused by Magnus in all pitches thrown in Major League Baseball.
The match ball for the 2010 FIFA World Cup has been criticised for the different Magnus effect from previous match balls.
The current ball is described as having less Magnus effect and as a result flies farther but with less controllable swerve. 
This type of spin is predominantly employed during service, wherein the contact angle of the racket can be more easily varied.
Unlike the two aforementioned techniques, sidespin causes the ball to spin on an axis which is vertical, rather than horizontal.
The axis of rotation is still roughly perpendicular, to the trajectory of the ball.
In this circumstance, the Magnus effect will still dictate the curvature of the ball to some degree.
Another difference is that unlike backspin and topspin, sidespin will have relatively very little effect on the bounce of the ball, much in the same way that a spinning top would not travel left or right if its axis of rotation were exactly vertical.
This makes sidespin a useful weapon in service, because it is less easily recognized when bouncing, and the ball "loses" less spin on the bounce.
Sidespin can also be employed in offensive rally strokes, often from a greater distance, as an adjunct to topspin or backspin.
This stroke is sometimes referred to as a "hook".
The hook can even be used in some extreme cases to circumvent the net when away from the table.