Asked by: Percy Jackson, Sri Lanka
Shoes that provide enough buoyancy to keep you afloat are simple but bulky. You’re really just cutting a raft in half and standing with one foot on each half.
Leonardo da Vinci sketched an idea for this in the 15th Century and it is a common school project for physics students. The hard part is designing shoes that provide enough traction to let you push against the water, without being so cumbersome that you exhaust yourself after a few steps.
But skipping over the surface, like the basilisk lizard (pictured) does, is much tougher. A 1996 study at Harvard discovered that the lizard strikes the water hard enough with each step that it creates a bubble of air surrounding each foot, and then pulls its feet up again fast enough to clear the surface before the bubble collapses, which minimises drag. When you scale the forces up to human size, you would need to run at over 100km/h (62mph) to pull this off. At least in Earth’s gravity.
A 2012 study at Rome’s Laboratory of Neuromotor Physiology found that if you wore flippers, and could find a suitable pool, you could run on water on the Moon.w
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