"If you think about two really really big guys and they lie on you with all their weight crushing you, that would be basically the kind of force they would be taking in at each impact when it is a proper shoulder to the body tackle."

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The expert said if Papalii was able to get up a head of steam and run at Waerea-Hargreaves at about 20kmh, with the Roosters prop close to stationary at about 4kmh, there would be a significant impact.

"It would be about the same as a motorbike hitting you at 15 kilometres an hour," Blazevich added.

And it could be worse from faster players in the NRL –among the top speeds recorded on the field in 2019 were Tyson Frizell (32.3kmh), Angus Crichton (32.76kmh) and Jake Trbojevic (31.3kmh), all of whom tip the scale over 100 kilograms.

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Papalii was freed to play in the grand final after a massive hit that was deemed fair on South Sydney's Adam Doueihi and NRL great Paul Gallen said the fearsome Raider was always a tough player to face. "He hits hard and he is a good player and has been the best player for the Canberra side this year," Gallen said.

Despite his hefty frame, the Canberra wrecking ball showcased his stamina by helping his team into the grand final with a heroic solo run for a 72nd-minute try against South Sydney, capping off his six tackle breaks for the match.

While some of the physicality and brutality of the sport has been eliminated, it is these tackles that ensure rugby league remains one of the most ferocious sports on the planet.

Imagine something that weighs about 200 kilograms and imagine if you were sitting under it.

Professor Anthony Blazevich

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Griffith University sports scientist Clare Minahan said players could hit an opposing defender with a force of about 10Gs.

G-force is a measurement of acceleration, Minahan explained, with 1G equal to the gravitational acceleration on earth which is 9.81 metres per second per second.

By way of comparison, an F-16 jet fighter pilot experiences about 9Gs when completing a barrel roll, while someone in a car accident at 65 km/h will be subjected to about 35Gs.

Minahan said the impact of tackles doesn't just depend on a player's size, but also the speed they are travelling.

"If the tackle occurs after a player has been travelling for a fair distance say over five or 10 metres the impact would be far greater as they are at a much higher velocity," she explained.

The associate professor said there are many variables that go into the force and outcomes of tackles or collisions but they can certainly do some damage.

"It is so variable but it is certainly enough to give an individual concussion, so that means the force is enough to cause some acute damage to the brain,"  Minahan said.

The clash between the Roosters and Raiders kicks-off at 7.30pm (AEDT) on Sunday.