Date: Tue, 23 Aug 2005 00:04:18 -0700 From: Julian Elischer <julian@elischer.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-hackers@freebsd.org, sos@freebsd.org, borjamar@sarenet.es Subject: Re: IBM Active Protection System Approach Message-ID: <430ACA72.7070303@elischer.org> In-Reply-To: <20050822.213857.78011913.imp@bsdimp.com> References: <A95A177C-8C1B-47F6-8344-B818F6A97EAF@FreeBSD.org> <5FFDC44D-F094-4856-8FAC-4D14EB77B47A@sarenet.es> <430A8E2B.6040408@elischer.org> <20050822.213857.78011913.imp@bsdimp.com>
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M. Warner Losh wrote: > In message: <430A8E2B.6040408@elischer.org> > Julian Elischer <julian@elischer.org> writes: > : You have about 1/4 a second to get the heads in once you detect that > : you are falling. > > Yes. For a 4' fall, we know it takes 1/2 a second to reach the > ground: > s = 1/2 a t^2 + v0 t + s0 > > s0 = 0, a = 32 f/s^2, v0 = 0, s = 4, solve for t gives 1/2 a second to > make the fall. Sos was saying 10's of ms to retract the heads, so > even a 300ms response time wouldn't be fatal, but it would be pushing > the limits. > > For a 2' fall, you have even less time. More like 350ms. 1' is 250ms... > > Warner I decided that you assume it's being picked up and slips out of your grasp and then dropped a pen from about 2' and said "yep, something like 1/3rd of a second.. I'll say something shorter than that" :-)
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