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# Re: "potential impact energy"

• To: <seaint(--nospam--at)seaint.org>
• Subject: Re: "potential impact energy"
• From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
• Date: Wed, 6 Oct 2004 22:13:29 -0500

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On Oct 6, 2004, at 6:08 PM, Gray Hodge wrote:

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Can anyone explain to me what is meant by "potential impact energy"? It is part of OSHA's fall protection standards. How do you calculate this?
It's the kinetic energy acquired by an object falling through some distance. The potential energy of the body equals the weight of the body (force, not mass) times the distance, and this potential energy is converted to kinetic energy as the object drops. So if a 180 lb worker is on a walkway 15 feet over a sidewalk, his potential energy is (180lb)(15ft) = 2700 ft-lb. More precisely, when the worker goes from the sidewalk to the walkway, his potential energy increases by 2700 ft-lb, since it's a relative quantity. If the guy falls, that potential energy converts to kinetic energy as he picks up speed, and this energy is absorbed by the pavement or the tie-off, whichever stops him.
```Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com    | this distance" (last words of Gen.
...................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/

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