Scientists reveal full force of collision with Josh Papalii

A Doctor of Biomechanics has crunched the numbers to determine the force of being hit by Canberra machine Josh Papalii, likening the impact to jumping off a three-story building.

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Cooper Cronk will suffer the equivalent of a nine metre fall every time he attempts to tackle Josh Papalii in the NRL grand final with science revealing the full force of a hit from the rugby league hulk.

In a mathematical revelation that proves the Canberra prop as the ultimate NRL destroyer, a Doctor of Biomechanics has calculated that being hit by Papalii is akin to jumping off a three-story building.

In an exclusive study commissioned by The Daily Telegraph on the eve of the do-or-die clash between the Roosters and the Raiders, Macquarie University Senior Lecturer Dr Tim Doyle revealed the prop puts almost 9,000 Joules of energy into every full-speed collision.

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Josh Papalii’s force on contact is enormous. Picture: Dave Hunt

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Standing at just 182cm, the 118kg forward has been clocked running at 33.3km/h.

“At 89kg Cooper Cronk is taking the equivalent of a fall from over nine meters if Josh runs into him,’’ Dr Doyle said.

“Based on his speed and size, Papalii would put almost 9,000 Joules of energy into a collision with Cronk. A nine-metre fall is how much energy is in that collision. All of that energy has to go somewhere, and in this case it is absorbed by the defender.’’

Previously employed as a human performance scientist for the Australian Defence Force, the physical performance researcher advised Cronk and the Roosters to become human air-bags.

“The players need to make sure that energy doesn’t hurt them,’’ Dr Doyle said.

Papalii will be key to a Canberra upset on Sunday. Picture: Mark Metcalfe

“And technique plays a big role in absorbing that energy in the collision. Just like airbags in a car, the energy has to go somewhere, so like an airbag and crumple zones in a vehicle, footy players need to learn how dissipate (absorb) this energy.

“If they do they’re fine. If they don’t they break.’’

Sydney University Professor of Exercise and Sport Science Ross Sanders also spoke about the science behind the Canberra steam train.

“Taking down a large player who is running fast directly at the defender is a daunting task for the defender and is associated with high risk of injury,’’ Sanders said.

Cooper Cronk and teammates have a daunting task of stopping Papalii. Picture: Joel Carrett

“Josh’s large mass relative to height is also an advantage as he would be very difficult to knock off balance due to the high mass and low centre of gravity. An attacking player prepares for a tackle by lowering their centre of gravity further by flexing at the hips and leaning in the direction of the force to be applied by a tackler.

“So being 118kg and only 182cm tall is a big advantage in an attacking situation.’’

Sanders revealed the math behind a rugby league collision.

“The player has momentum that has to be reduced to zero,’’ Sanders said.

“Momentum is mass multiplied by velocity. The player is advantaged by having lots of mass and so at equivalent speeds will have more momentum than other players.

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“A change in momentum is achieved by applying a force for a period of time (change in M = FxT) – the higher the force, the greater the change in momentum for any given time.’’

So how would a scientist tackle Papalii?

“Tackling players should make initial contact with the runner’s hip and upper thigh area from the side,’’ Sanders said.

“And then ‘slide down’ pulling the thighs together. However, that is not always easy when tackling a player of Josh’s dimensions. The other strategy is to knock them off balance so that they fall over and then much of the force to arrest their motion is provided by the ground rather than the player.

“This is probably easier for the tackler if it is done from the side rather than from in front in which case the charging player can run straight at them and knock them backwards possibly retaining their balance and continuing to drive forward.’’

Sydney University physics professor Rodney Cross estimated Papalii could generate over 5Gs of force. A “G-Force’’ is a force acting on a body as a result of acceleration and gravity.

Former Panthers prop Tim Grant declared Papalii a nightmare to tackle.

“Without doubt one of the hardest guys I have defended against,’’ Grant said.

“And it is not just his power. He also has speed, footwork and an offload. With someone like Dave Klemmer, you know what is coming. He will just line you up and try and go through you. Papalii might do that, but he may also bump, step, or pass. He has so many weapons.

“I don’t know how the smaller blokes deal with him. I guess they just become speed bumps. He is like a car crash’’

Originally published as Scientists reveal full force of collision with Josh Papalii