“The impact of the elevator at the bottom of the shaft would subject you to extreme gravitational acceleration, or G-forces,” Dr. Frank explained. “The number of G’s you experience multiplies your normal weight, so if you experience 10 G’s, you would experience 10 times the weight of your body.

“You might think that bracing yourself or bending your legs would help, but at high G-forces, your legs would simply not be able to support the weight of your body,” he said. “Even the weight of your own head would be too much for your neck to support.”

The folk wisdom of jumping up at the moment of impact is convincingly debunked in a “MythBusters” video on the Discovery Channel Web site. It would not work unless you could know the precise moment of impact and leap at the same speed the elevator is plunging.