article_snippet.sent: the Rapa Nui people believe that the hats, or 'pukao', were rolled up ramps to reach the top of the figures which measure up to 40ft (12 metres) tall.
article_snippet.sent: A tall order: Physicists believe that the pukao, or 'hats,' were rolled up ramps to reach the top of the figures (examples are pictured left and right), some of which measure up to 40 ft (12 metres) tall .
article_snippet.sent: Mr Hixon’s team used basic physics to model the force and torque required to place a pukao on a Moai’s head, using different techniques.
article_snippet.sent: These concluded that the rounded oblong shape of An estimated 100 pukao means that it would have required relatively little energy to roll These up a ramp.
article_snippet.sent: However, while the team thinks ramps were the most likely method for the placing of the hats, the hats models revealed that any of the proposed methods for raising An estimated 100 pukao would have been possible - with enough manpower.
highlights_snippet.sent: Oregon University used physics to model possible methods of raising the 'hats'
  Some 100 pukao have been found on the remote  island in the Pacific Ocean .