minitour said:
I think he's talking about the "error" with the angle of view...
...kind of like line of sight with satellites or maybe more relevant slant range error with DME...you know...if you're angle is weird maybe your perception on the point where he crossed the line is weird...
...im sure someone somewhere could make a case if they were clocked a LITTLE over the speed limit...but at 200+ mph....the guy running the stopwatch would have to be having a seisure to have stopped it early enough to make a difference...
-mini
I think he's referring to parallax error, the error that occurs from viewing the target and the guage from an angle when the target and the guage are offset. Read a conventional car speedometer from straight ahead (the driver's seat) and the speedometer reads 65. Read the same speedometer from the passenger seat and it read 58 (for example).
Parallax error is only a problem when the target (in this case the motorcycle) and the guage (the white line) are offset, or seperated some distance from one another. Since the motorcyle passes directly over the marks, there is no distance, and therefore no parallax error.
Since the stop/start times were triggered by a thumb, and not an electronic sensor of any sort, the angle is insignificant.
EDIT:
The method is quite simple, by the way. You can work through the algebra if you like, but it boils down to this. For a quarter mile (as specified in this case) one should divide 900 by the number of seconds it takes to travel the distance.
900 / 4.39 = 205.01, so 205 mph
Mess up the timing by a whole second ( 900 / 5.39 = 166.98, so 167 mph) and you still have a hefty ticket. Mess it up by a whole second on either end, (900 / 6.39 = 140.85, so 141 mph) and the guy's still twice the speed limit and he's still goin' to jail. I think the judge will allow it.
