Jonah Lomu: A Force to Be Reckoned With
At 270 pounds during his playing career, Jonah Lomu was the average size of a rugby prop. Props tend to be some of the strongest players on the field, but they are certainly not known for their speed. A rugby wing is normally one of the smallest players, yet fastest, players in the game. Lomu defied the norm by being both one of the largest and quickest players on the field. He was known for this incomparable combination. In high school he ran 100 meters in 10.8 seconds. For comparison, Usain Bolt ran it in 9.63 seconds. The slowest man in the 2012 olympic final ran it in 9.98 seconds. Lomu's speed is extreme when the sheer size of this body is taken into account. Rugby wings are also not normally world class sprinters; they must have a combination of agility, speed, and technical skill. Lomu had all of this as well as brute strength.
The following video shows Lomu's strength and speed in a collaboration of his greatest tries (a "goal" in rugby). It also has cheesy, inspirational music. Lomu is the man wearing a jersey with "11" that repeatedly plows through other players.
(Photo from: http://www.telegraph.co.uk/sport/rugbyunion/international/newzealand/11210454/Jonah-Lomu-is-the-Muhammad-Ali-of-rugby.-Julian-Savea-will-never-match-him.html)
Jonah Lomu is considered one of the greatest wings of all time. He was such a force to be reckoned with because of a combination of his speed and size (pun intended). His mass was about 100 pounds greater than the average wing, 150-180 pounds versus his 270. Because Force=Mass*Acceleration, and Jonah Lomu had both the ability to accelerate very quickly and a high mass, he acted with a much greater force than the average wing.
In Rugby, defense is set up in a way that normally a position will normally defend against own position on the other team. The tackler should have a greater acceleration than the ball carrier because the tackler will have had a quick burst of speed to meet the ball carrier who has already been moving at pace. An average wing will be in somewhat similar mass to his opposition. The tackler will exert a greater force on the ball carrier because of the increased acceleration and similar mass. This will enable them to complete the tackle or slow the ball carrier enough for additional defenders to do so. Jonah Lomu had such a great mass, that even if the tackler had a higher acceleration, Lomu would still exert a greater force. He would simply storm through defenders, using an incredible stiff arm to easily push them aside.
(Photo from: http://physicsinrugby2012.weebly.com/kinetics-and-forces.html)
Not only did Jonah Lomu exert a greater force on the other wings, he also moved with a greater momentum. He had both a greater mass and a greater velocity than the defender he would encounter. Defenders have a high acceleration because they are normally acceleration from rest to meet the ball carrier from the off-side line. The defender will have a lesser momentum, though, because they will not have reached a speed as great as the ball carrier who would have been moving at pace from a deeper position.
(Photo from: http://ncvs.org/e-learning/equations/chapter2/index.html)
The picture below shows how defense is set up. The wings (number 11 and 14) will be set in a staggered line, and the ball will travel down the line while the players run forward. The wing will catch the ball while already sprinting, and try to run up the side through the defense's flat line. The defense will be stand on the off-side line (imaginary flat line across the field) and accelerate from rest to meet the attacking players.
(Photo from: http://www.wilkesbarrerugby.com/theGame/)
The 1995 world cup final was played between South Africa and New Zealand. South Africa practiced specific defending when dealing the Jonah Lomu. They would herd him to the side line with multiple players attempting to make a tackle at once. This left the far side of the field more open with an outnumbered defense. However, it was the only way to stop Lomu from scoring try after try.