The 2016 Olympic Games are finally upon us, bringing the best athletes in the world to Brazil for 17 days of international competition. This year's extravaganza will feature 42 sports played in more than 300 separate events. But none, arguably, is more terrifying than diving.
Well, for those of us afraid of 10-meter drops, anyway. Better not to think about it, and focus instead on the physics involved. Trace Dominguez does just that in today's edition of DNews, Whether jumping off a springboard from three meters up, or a platform ten meters up, the initial leap is all-important for divers. Competitors need to clear the platform horizontally, of course, but also need to get maximum vertical lift. This angle of attack will determine the arc through which the diver moves before hitting the water.
Then there is the matter of rotation. The inertial impetus of all the diver's subsequent flips and twists must be present in that first leap. From there, they can increase the speed of spinning by drawing the body into a compact ball. This tuck position reduces the body's tendency to resist angular acceleration. Other physics-based concepts like rotational speed and angular momentum come into play as well. But the upshot is that Olympic-caliber divers can squeeze four-and-a-half flips into 1.5 seconds of fall time. Crazy talk.
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After 10 meters of twisting, flipping and falling, divers reach speeds of around 50 kilometers per hour by the time they hit the water. The goal is to slip into the water with as little splash as possible -- a rip entry, to use the industry jargon. To achieve this, divers need to get as straight and as vertical as possible in that final split-second.
Keep in mind that divers are still spinning, twisting and moving in an arc when they hit the water. In fact, continue they continue on those inertial paths under the water. The trick is to straighten out during that microsecond of impact and give the appearance of a smooth vertical entry. It's tricky, all right.
For more on the endlessly complex interplay of physics and sports, check out Julian Huguet's report on gravity, air pressure and baseballs.
-- Glenn McDonald
Wired: Olympic Physics: Diving And The Moment Of Inertia
New York Times: A 'Rip' Dive Brings Points And Pain
It's Okay To Be Smart: Biomechanics Of The Perfect Olympic Dive