How does tampering with cricket ball effect its trajectory ?
“The yellow tape”. This has become the latest trending word after an Australian cricketer was caught red handed while tampering the cricket ball and trying to change its condition. He used a yellow tape to roughen the surface of the ball so that it can “Reverse swing” and make batsmen suffer. Though the entire social media is revolving around the issue of ball tampering in a game’s perspective, ball tampering has got a lot to do with aerodynamics and science. Many people, including die hard fans of cricket have very less knowledge about why cricketers do ball tampering, in a scientific perspective. This article is aimed at exploring the reason for ball tampering and how a wonderful phenomenon called “Swing” happens when a ball is tampered.
In the sport of cricket, ball tampering is an action in which fielder illegally alters the condition of the ball. A standard cricket ball weighs 5 1/2oz, interior made of cork, wound round with a string. The outside consists of red leather stitched around its circumference, creating a raised seam. Polishing the waxed leather surface on the body or clothing and drying the wet surface with a towel is legally accepted in cricket. This can be observed in almost all the test matches. However, they are forbidden from applying any substance other than saliva or sweat to the ball, and are also banned from deliberately scuffing or roughing it, or picking at or lifting the seam. Cricket is a game that involves passing ball from one person to another very frequently. Thus, there is a huge chance of ball getting tampered by any of the player. Umpires are responsible to monitor the condition of the ball regularly. However, it is virtually impossible to keep an eye on the ball all the time. Moreover, tampering can be done in a matter of seconds, that can lead to the act going unnoticed.
Now, coming to the scientific side of ball tampering, there is a lot of aerodynamics involved in it. When a ball is new, the leather is equally shiny on both sides of the seam, and will usually deviate on its flight through the air. As the innings progresses, the surface deteriorates through contact with the bat, ground, and advertisement hoardings. However, the fielding side will usually attempt to keep one side of the ball as pristine as possible. If it becomes significantly shinier than the other side, it will start to do interesting things after it leaves the bowler’s hand. The half that is slick and shiny meets little wind resistance when it is thrown; the other side (which is battered, with small bits of leather protruding from its surface) travels less easily through the air. As a result of the varying wind resistances, the ball will fly in a curved direction, a phenomenon known as “swing”. . Uncertainty over the direction and distance that the ball might deviate makes it harder for the batsman to hit it. Tampering with a ball by illegally roughing it up, or by polishing it with banned substances, will exaggerate the extent of this “swing”.
In addition, bowlers will usually attempt to make the ball “pitch” or land on its seam, so that it will deviate slightly on landing. Illegally picking or lifting the seam will exaggerate the extent of this further deviation.
Coming to the “Reverse swing”, it is usually called the holy grail of fast bowling. This generally occurs when a ball becomes very old, and its aerodynamics change to make it swing towards the polished side. This is because the air begins to flow turbulently around both sides of the ball. The angled position of the seam causes the airflow to separate earlier on one side than the other, altering its direction accordingly. Reverse swing is hard to achieve, and generally only occurs in hot, dry weather conditions, after a ball is 40 overs old.
Ball tampering is useful only for the fast bowlers. Slow bowlers try to change the direction of the ball using their fingers or wrist, which is called spin. Though ball tampering is a serious issue and needs an immediate attention to protect the integrity of the game, the science involved in it is very fascinating. Hoping that ball tampering will be stopped in future and this beautiful and wonderful game that involves a lot of science be flourished and cherished by each and every cricket fan.
To know more about the aerodynamics behind swing, go through the following links:
