ORIGINAL: Patrick_
ORIGINAL: haasjj
ORIGINAL: Patrick_
Simply set up a drag of X feet, have someone time the run, and calculate it from there. For best results (to lessen the effect of latency of human reaction on the speed/time), set up a longer drag.
Measure out say 100 feet. Give yourself Y feet of initial run before the drag. Time it, and then calculate it.
(LENGTH_FT/TIME_SEC)*(1(mi)/5280(ft/mi))*(60sec/1m)*(60min/1hr)
So if you've got a drag of 100 feet and your truck finishes it in 2.25 seconds:
(100/2.25)*(1/5280)*(60/1)*(60/1) = 30.3MPH
Your math is wrong, I'll give the correct answer when I gat a chance to.
Heh, actually, my math is correct. Maybe putting it in this form will help:
100
ft x 1 mi x 60
s x 60
min
----------------------------------
2.25
s x 5280
ft x 1
min x 1 hr
This equals 30.3mi/hr.
Weather the math is right or not (and I have not bothered to check) is really irrelevent. Reaction time and paralax can mean that the timing can be off 1/2 a second or more. Which makes this method good only for an approxamate speed. The best method would be an electronically triggered speed trap - similar to what appears to be being used in the dragster video.
I have also heard of people video taping a speed run through a measured distance and counting the number of video frames and using the frame speed to calculate the speed of the car.
Still much of the numbers reported are subject to peoples desire to be the best/fastest and so much can be altered electronically that it's very hard to trust any stated speed figure. That may just be my opinion though, idk.