I just learned some new information that help determine speed if the point
of impact is before the car would come to rest under "normal" conditions.
You need a few factors:
Weight of "Taget Vehicle": Say 4800 lbs
Weight of "Bullet Vehicle": Say 3200 lbs
The deviation: 30 feet
Drag Factor .355 G
The Target Vehicle would be traveling 21.86 mph
Now this is only if the "Bullet Vehicle" is at a stand still.
-Dakota
>
>Ill get back on it shortly with an answer for you.
>
>-------------
>Dakota Dodge
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>Truck Home Page: http://www.dakota2.4mg.com
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>>I've always wondered about that - determining vehicle speed from skid
>>marks. I know it makes sense based upon physics - take the weight of the
>>vehicle and then measure the skid marks to determine the speed of the
>>vehicle, etc. What has always been a question in my mind, though, is
>>suppose the person is a little slow in the reflexes and the skid marks
>>are short because the impact happened more suddenly? In other words, say
>>in normal conditions my reaction time is .32 seconds, but some chick
>>distracts me and when I finally turn my attention back to the road ahead,
>>I'm about to impact another vehicle. Under normal circumstances I would
>>have begun to apply the brakes maybe 30 yds sooner and my skid marks
>>would have been longer. As someone knowledgeable in this area can you
>>enlighten me as to how the speed can be determined when one never really
>>knows the reaction time of the driver leaving the skid marks and the fact
>>that the driver may have impacted the other vehicle before running out of
>>skid?
>>
>>Thanks!
>>
>>Richard in San Antonio
>>
>>
>>On Thu, 12 Jul 2001 16:58:08 -0000 "Dakota Dodge"
>><dakotasdodge@hotmail.com> writes:
>> > As a safety engineer, along with my dad, we have looked at many MVA's
>> > (Motor
>> > Vehicle Accidents) in the past and I would guess 95% of them all
>> > have one
>> > thing in common. And that is they leave tire (skid) marks from the
>> >
>> > accident. Those that can control there brakeing and stay in control
>> > without
>> > skidding will be MUCH LESS likely to be involved in a crash. The
>> > coeficient
>> > of friction for tires is approx .95, and once they start to skid
>> > (which if
>> > you look at it in slow motion...the tires are skidding on the
>> > burning
>> > rubber) the coeficient of friction drops down to the area of water
>> > (ever
>> > hydroplaned in your DAK?...same idea as skidding on rubber)
>> > Well there. A little in depth stuff for any of you interetsted.
>> > BTW - if
>> > you are ever in a car wreck and leave skid marks and there is a
>> > question
>> > about your speed...through the use of the coefficent of friction the
>> > police
>> > (or myself as an investigator) can tell if you were speeding or not.
>> > Pretty
>> > neat stuff huh?!
>> >
>> > -------------
>> > Dakota Dodge
>> > Profile at:
>> > http://www.twistedbits.net/WWWProfile/dakota/XgAJPmbQu2jpA/profile.htm
>> > Truck Home Page: http://www.dakota2.4mg.com
>
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