Well, this week, as usual, I am again not actually "at work." I am taking a one week crash investigation class put on by the highway patrol. I haven't been at work in quite some time, but plan to be back on Saturday. The crash course is fun, its definitely my cup of tea. Just finished the second day of it. We did all formulas (math) on obtaining measurements, speeds, drag factors, coefficient of friction adjustments, critical speeds, airborne speeds, and a little more. This course is just the first level of many, but most cops don't even get this one. Most cops go through the academy crash hours and that's the end, so this starts getting more in depth. I will probably go through all the crash courses to reconstructionist, which I hear is pretty hard. For now, having fun with this class. Just for fun I'll give you one of the problems we worked out today (all classroom, so some information given instead of us taking the measurements).
Ex: A vehicle departs the roadway and enters a yard where it becomes airborne off of a flower bed. Grade measurements were taken on the flower bed where the vehicle left the ground. Using a four foot level, the uphill grade produced 5 inches of rise. After departing the ground, the vehicle traveled 34 feet 5 inches horizontally and dropped 2 feet 11 inches. Determine the speed of the vehicle at take-off.
Another for kicks?
Ex2: A car strikes a pole at 49 mph. Prior to impact it skids an average distance of 82 feet on asphalt with a drag factor f= .69 and grass for a distance of 13 feet 2 inches with a drag factor of f=.33. What was the speed of the vehicle at first braking.
Answers:
Ex: 37.058MPH (true speed)
Ex2:65.028MPH (lowest possible speed)
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2 comments:
Okay, for the first answer, I got 36.957 mph. Of course, the number of significant digits depends on how good your measurements were. :)
The answer to the second problem is 64.9885 mph. The car was traveling at 50.3 mph when it hit the grass.
I would also like to state that I am disappointed in the fact that the crash investigation class seems to use British units instead of the standard SI units (ie. meters not feet). This is the 21st century, you would have thought we would have moved on to the more standard set of units by now. I guess it show what kind of country we live in: stubborn.
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