Empirical Search for Suitable Experimental Periods for Gravitational Acceleration Determination
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Date
2012
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Faculty of Science University of Ilorin, Ilorin
Abstract
Variations in the acceleration due to gravity, from place to place on the earth's surface are caused by parameters such as inequality of earth’s radius from pole to equator, temperature variation, density variation in the subsurface rocks, and many others. Hence, this work examined practically the temperature effect to determine the appropriate period when acceleration due to gravity could be determined with the least adverse effect of the diurnal temperature instability. Experiments were carried out in the laboratory. First diurnal temperature variation with time was monitored with a digital thermometer for two days from which three suitable experimental periods were determined as 2:30 am, 2:45 pm and 8:30 am, indicating the coldest, hottest, and moderate temperature periods. The free oscillation simple pendulum method was used to determine the acceleration due to gravity (g) at the periods identified above for 3 weeks. The values obtained were compared with 9.78031225 ms-2, the standard absolute gravity value obtained at the school of Aviation Technology, Zaria; the value which was tied to international standardization Net, (IGSN71) through Primary Gravity Network for Nigeria (PGNN85) An average of 9.74651200 ms-2 was obtained at 8:53 am (coldest period). 0.3% deviated from the standard, 9.72281780 ms-2 was obtained at 2:45 pm, a deviation of about 0.5%, and the largest deviation of 0.70% occurred at 2:30 am. It was concluded that a consistent and reliable acceleration due to gravity could be determined around 9:00 am to 2:40 pm. However, measurements around 2:30 am could surfer spurious variations.
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Keywords
Absolute-Gravity. Time-window. Laboratory. Pendulum. Experimental-Gravity