While insects are small enough to use surface tension to stay atop water, larger species like the basilisk lizard run on water by slapping their feet against the surface hard enough to generate the force to stay above the surface. A. Minetti and colleagues won this year’s Ig Nobel Prize in Physics for demonstrating that humans, too, can achieve this feat – when outfitted with stiff, large area fins and exposed to gravity less than 22% of Earth’s. The researchers adapted a model for the running lizard to human scales and then tested the model using subjects suspended by harness and running in place atop a wading pool while subjected to various lighter-than-earth simulated gravities. Both the model and experiment agreed that human muscles were unable to produce sufficient force to stay above the water at higher than 0.22g. Interestingly, the authors also observed that the water-running gait for both lizards and humans has more in common with the pedaling motion of cycling than a human’s bouncing gait for terrestrial running. (Video credit: A. Minetti et al.)
Ig Nobel Fluids: Running on Water
