Re: University Physics

[Larry Woolf <larry.woolf@GAT.COM>]

Some additional information on reaction times with some nice ways of
presenting this information - that I use in my unit - is at:
<http://www.nhtsa.dot.gov/people/outreach/safesobr/pub/deadly.pdf>

It is interesting to compare stopping distances of sober and drunk drivers:
drinking (or talking on cell phones) doubles the reaction time.

Larry Woolf;General Atomics;6995 Flanders Dr.;MS 78-107;San Diego CA
92121-2975; Ph:858-526-8575;FAX:858-526-8568; www.ga.com; www.sci-ed-ga.org

-----Original Message-----
From:  Hugh Haskell
Sent: Tuesday, September 24, 2002 1:37 PM
Subject: Re: University Physics

At 12:47 -0700 9/24/02, Larry Woolf wrote:
> Headlights illuminate the road up to 160 ft in front of you.  If you are on
> a road with stop signs, what is the fastest speed you can drive and still
> stop safely at night?
> A typical reaction time for braking is 1.5 s (See Traffic Safety and the
> Driver by Leonard Evans) and a typical braking acceleration for a car is 17
> ft/s2.

So I might modify Larry's problem to specify an alert driver, and
give a reaction time of .5 sec, then add a part (b) to specify an
inattentive driver with a reaction time of 2.5 sec. The difference in
safe speed for these two cases would be quite dramatic (somewhere
around 20 mph).