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Modern weighing practice consists of making comparisons between the gravitational attractive forces exerted on standard and unknown weights. An effect coupling the gravitational force exerted on a weight to the height of the weight’s center of gravity above its base has been found to be significant when weighings of the highest precision are attempted. This effect will cause systematic errors in mass measurements if not properly accounted for. The effect, called the ’’gravitational configuration effect,’’ arises because the centers of gravity of nominally equal weights above their bases, and hence the weights’ effective distances from the center of the Earth, are affected by the weights’ size and shape. Variations of 1 cm in the separation between the centers of gravity of weights and the center of the Earth produce differences in gravitational attractions of 3.14 parts in 109. Currently, mass comparisons at the 1-kg level can be carried out with standard deviations as small as 1.5 parts in 109. Thus, the gravitational configuration effect must be considered if weighing accuracies approaching weighing precisions are to be obtained when kilogram weights of significantly different sizes and/or shapes are compared. Corrections for the gravitational configuration effect can readily be combined with corrections for better-known effects, such as air buoyancy, to generate an overall equation to express the results of mass comparisons.

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The influence of projectile strength on cratering was investigated for projectiles of aluminum alloys impacting semi-infinite aluminum targets over the velocity range of 1 km/sec to 5.0 km/sec. The experimental results showed that crater diameters were not significantly influenced by varying projectile strength. The crater depths were found to vary appreciably with strength at lower velocities but to become virtually the same at 3.5 km/sec for the series of projectile alloys investigated. A simple dynamic model for cratering was developed and compared with the experimental results of this study and other experimental results at higher velocities. These comparisons showed that the model provided predictions of crater diameter which were within 8 percent for the experimental results of this study and within 13 percent for the hypervelocity data. Crater depth predictions showed good agreement with the experimental results of this study for projectiles having greater yield strength than the target material. The predictions of depth as a function of velocity showed qualitative agreement with the hypervelocity data.