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The world's most fantastic falls.

Stories like those on the opposite page are tough to believe. After all, thousands of people die each year when they fall from much lower heights, such as from ladders and stairs. How did Chissov, Saggers, and Boyer beat the odds?

Hint: Think back to the last time you took a painful spill. Did you fall on hard concrete or soft grass? What hit the ground first--your cushioned backside or bony elbows?

The bottom line: "Whether or not you get injured in a fall really depends on how you land," says physics teacher Lewis Love.

TOUCHDOWN

Safe landing rule #1: Hit something that will bring your body to a gradual stop. Why? The longer it takes to land, the less concentrated the force acting on your body will be at any given instant during the impact. Instead of absorbing a sudden bone-crushing, organ-splattering wallop, your body will receive a longer-lasting, weaker blow.

But we're not talking minutes--or even seconds--here. The difference between dying and walking away unscathed can be measured in mere fractions of a second.

Take Boyer. If she had landed on solid ground, she would have come to a crashing halt in about 0.001sec. The concentrated force of that abrupt landing would have killed her instantly.

But luck was on Boyer's side--sort of. She landed in the sludge pond of a sewage treatment plant. The soft, squishy sludge brought her body to rest in something like 0.03sec--30 times longer than if she'd landed on solid ground. Because the force of the impact was distributed over this longer time, it was never strong enough at any instant to cause her serious injury.

A gradual landing saved Chissov's life as well. On impact, he slid down the side of a steep, snow-covered ravine. The friction from sliding and the deep snow brought him to a gradual stop.

And Saggers? Well, the top of a car might not sound like the cushiest of landing surfaces. Eye-witness Paul Eardley certainly didn't think so. He was nearby when Saggers fell. "I heard this terrific bang and glass went flying. The car was flattened like a pancake," he says.

In other words, the collapsing car absorbed some of the force of Sagger's fall. He kept moving downward, crushing the car beneath him, losing speed as he went. In all, his spectacular landing lasted about 0.24sec--a nice long time, as landings go.

ALL SPRAWLED OUT

But, there's more to a safe landing than a "soft" surface that slows you down gradually, says physicist Arthur Damask. Happy landing rule #2: Distribute the impact force over as large an area as possible.

If Saggers had hit the roof feet first, all the force would have been concentrated in one small area--his feet. This focused force would have shattered Saggers's legs and driven the bones of his hips through his spine. "At the very least, he would have been paralyzed for life," Damask says.

But Saggers landed sprawled out, with the force of impact distributed evenly over his body, so he was able to get up and walk away. (Chissov wasn't quite as lucky. Though the snowy slope saved his life, he still suffered a broken pelvis. It took him three months to recover.)

The unfortunate thing about falling, of course, is that you usually don't have control over when or where it happens. So unless you plan to bring a parachute everywhere you go, keep your eyes open, and watch your ste-e-e-ep!

WHY THINGS FALL

The force behind all falls is the same--gravity. That's the downward pull that Earth exerts on all nearby objects.

To keep an object up, you have to exert an upward force to oppose gravity's downward pull. Without the force exerted by your muscles, for example, your body would tumble down.

Would you tumble faster if you were heavier? People thought so until Italian physicist Galileo Galilei proved them wrong in the seventeenth century.

According to legend, Galileo dropped bronze balls of different weights from the Leaning Tower of Pisa, letting go of them at the same time. (In reality, he rolled them down an inclined plane.) All the balls hit the ground at once. So Galileo concluded that their weight had no effect on their falling speed. All objects falling toward Earth, we now know, speed up 9.8 meters per second for every second they fall.

At least, that's how it would work if gravity were the only force involved. But more often than not, other forces interfere. On Earth, for example, falling objects crash into countless air molecules. These molecules push up against the object, resisting its fall. The larger--or more spread out--the object, the greater the number of collisions, and the greater the air resistance. That's why a flat sheet of paper will fall to the ground more slowly than one that's wadded up into a ball.
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Title Annotation:how three people survived falls; includes related article on the physics of falling
Author:Plaut, Josh
Publication:Science World
Date:Sep 3, 1993
Words:811
Previous Article:Keepers of the deep.
Next Article:How to launch an experiment.
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