Last weekend, a 1-year-old girl in Switzerland survived a 100-foot fall in a cable car. A man survived a 500-foot fall from a New York City skyscraper. When the 35W bridge collapsed in Minneapolis, 13 people died, but many more survived the more than 100-foot fall. Even 2 percent of those who jump off the Golden Gate Bridge live.
How is it possible?
Although there are too many variables for a simple answer, physics explains a lot of it. Jim Kakalios, a physics professor at the University of Minnesota and author of "The Physics of Superheroes," says there are two main factors that can make survival more likely: maximizing air resistance, and maximizing the time it takes to slow you down.
“A cable car has the aerodynamics of a brick,” he pointed out. “You have a large amount of potential energy at the top when the cable breaks, and the kinetic energy when you land is where the damage comes from. But instead of (all the energy going into) speeding up, some of the energy goes into the work of moving the air out of the way of the car. It was similar when the 35W bridge collapsed; the bridge span had to do all this work to push the air and support structures away.”
Video of the bridge falling shows it took four seconds.
“That’s twice as long as if it’d been in a vacuum,” he said.
Another way to think about the Switzerland accident: A cable car is about the size of a small car, Kakalios said. The cable car would have been going about 60 miles per hour on impact, he calculates. People survive car crashes of that speed, especially if air bags slow down the impact.
“Let’s say that the time to slow you down from a collision increases from one millisecond to three milliseconds,” Kakalios said. “That’s still really fast, but it’s three times as long, so you hit with a three times smaller force -- a force that would have killed you, now won’t.”