- 行业: Earth science
- Number of terms: 93452
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Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
The capacity of a system for doing work by virtue of the velocities of the various moving masses in the system. The kinetic energy (k. E. ) of a body of mass M moving with velocity v is ½ M v 2. It is equal to the work that would have to be expended to bring the body to rest. It is additive, in the sense that the k. E. of a system composed of several moving bodies is the sum of the k. E. S of the individual bodies. A distinction is sometimes made between a body's internal k. E. and its external or mechanical k. E. The internal k. E. is the sum of the k. E. 's of the individual particles making up the body, with respect to a coordinate system fixed in the body. The external k. E. is the k. E. appearing as translation and rotation of the body as a whole in some external coordinate system. Unless stated otherwise, kinetic energy means external kinetic energy.
Industry:Earth science
A system is said to be in thermo-dynamic equilibrium when its entropy is a maximum.
Industry:Earth science
A line, other than the equator, on the reference ellipsoid and to which angles analogous to latitude are referred.
Industry:Earth science
(1) The work done in changing a physical system from one distribution of masses and velocities (state I) to another (state II), if the same amount of work can be recovered by the system's changing from state II to state I. Such a system is called a reversible mechanical system. (2) The work done in changing a physical system from one distribution of masses and velocities (state I) to another (state II), if the work done is a function only of the initial and final configurations and not of the trajectories along which the work was done. In speaking of systems composed of point masses, the phrase a function only of the initial and final coordinates of the masses is often used. The two definitions are almost equivalent, and both are referred to as definitions of mechanical potential energy or, if no confusion is likely, as definitions simply of potential energy. (3) The difference in mechanical potential energy of a body at two points P and Q is the amount of work done in moving that body from P to Q. It is, for a point mass, the product of the mass of the body by the negative of the difference in potential at the two points.
Industry:Earth science
A chart showing the necessary extensions of lens system and copyboard required for various enlargements and reductions.
Industry:Earth science
The distance of a point above an arbitrary, specified surface of reference, taken along the vertical through the point.
Industry:Earth science
The value HnoN calculated for the elevation of a point PN according to the formula <br>
Industry:Earth science
A unit of measure for rate of change of acceleration with distance i.e., the gradient of acceleration. It has magnitude and dimensions 10<sup>-9</sup> m/(s²m) or 10<sup>-9</sup> cm/(s²cm). The quantity is sometimes given as 10<sup>-9</sup> s<sup>-2</sup>. This form is dimensionally correct but physically wrong and should not be used. The Eötvös unit is used principally in expressing values of gravity gradient. Gravity gradiometers typically have sensitivities of 0. 1 to 1. 0 Eötvös units. E. U. and E have been used as symbols for the unit; the former is preferred.
Industry:Earth science
One of the elements, of an orbit adopted as reference, which approximates the actual, perturbed orbit. Mean elements serve as the basis for calculating perturbations.
Industry:Earth science
