Any fool can see that tackling Parramatta's runaway prop forward Fuifui Moimoi is hard. It takes a scientist to tell you how hard.
Imagine standing looking up at the sky. From a leaning tower someone drops a 20 kilogram bag of cement from a height of 22 metres. Dr Nicholas Armstrong, a physicist, says that when you try to catch the cement it will have the same energy as Moimoi generates when he surges into the defensive line.
The Tongan-born Moimoi, who stands 183 centimetres tall and weighs 110 kilograms, has led Parramatta's charge into the grand final with opposition sides frequently finding him unstoppable. Little wonder.
Momentum equals mass times velocity and, while Moimoi's weight is typical for his position, his speed sets him apart.
Moimoi is able to accelerate from jogging pace to 26 km/h within two seconds. His top speed on a treadmill is 31.2 km/h and he has been measured at 32km/h in game situations.
Of course, it is nothing like Usain Bolt, the world record holder for the 100 metres, who reaches 43.9 km/h, but combined with his mass, Moimoi is a deadly weapon. He is one of the three fastest Parramatta players in a 40-metre sprint.
Maybe it's what he eats.
''He's the horse in our team,'' said the Eels centre Krisnan Inu. ''He loves to eat it, so that's why he runs like one.''
He eats like a horse? ''No, he eats horse,'' Inu said.
''It tastes nice. Every islander eats a bit of horse.''
Moimoi, who will carry a cracked rib and crook knee into the game, shook his head in a non-committal way when asked about his eating habits, although his mother Manise is visiting from Tonga and has taken over the cooking to ensure her little boy has plenty of stamina.
Dr Anita Sirotic, a sports scientist with the Parramatta Eels, says Moimoi is hitting the defence with a force of more than 14 g (1 g is the acceleration due to gravity; fighter pilots experience forces of 9 g but, sustained for more than a few seconds, 4-6 g is enough to induce blackout).
In the grand final on Sunday against the Melbourne Storm, she expects Moimoi will experience more than 60 collisions with impacts of more than 9 g. John Baker, a senior biomechanist at the Australian Institute of Sport, said 14 g was ''massive - that's an extreme hit'', with the effect compounded during a game.
''If you added them all up [60 collisions] it would be like being hit by a six-tonne truck at 30 km/h,'' he estimated.
