Greetings to all,
AB = 463.86 m as measured at 4C. The corrected length is 463.77 m. (463.86 x Correction Factor). The correction factor is less than 1 when the temperature is less than 20C.
Correction factor = 1 + (.0000116 x (T° -20)) = 0.99814 for 4C.
Why? The tape contracts when temperature is less than 20C. When it is read at point B it indicates a figure greater than the true AB. (the reading at 20c will be less than the reading at 4C).
See the figure below to aid understanding.
This figure appeared in Measurement News, August 1986
46 responses were received from 14 countries. 40 were correct (463.77 m) and 6 incorrect (463.94 m). 8 people changed their answer after thinking about it. 7 gave a correct revised answer and one gave an incorrect revised answer.
Responses were received from the following countries: USA 17, France 15. One each from Australia, Brazil, Canada, Great Britain, italy, Morocco, Poland, South Africa, Switzerland and Turkey.
Among the 28 non-USA responses were AIMS/IAAF approved measurers. (18 grade A and 13 grade B, and 18 national level measurers).
Recorded errors included 2 from “A” measurers, 2 from “B” measurers and 2 from national level measurers
Thanks to all who participated in this study.
Jean Francois
Translated by Pete Riegel