| 释义 |
gravitational, a.|grævɪˈteɪʃənəl|
[f. gravitation + -al1.]
a. Of, pertaining to, or caused by gravitation; employing the principle or law of gravitation (sense 2).
gravitational astronomy: a system of astronomy based, as by Sir Isaac Newton, on the theory of gravitation; also called theoretical astronomy; so g. astronomer.
1855B. Powell Ess. 78 All kinds of physical agents..thermotic, electric, chemical, molecular, gravitational, luminiferous. 1869Dunkin Midn. Sky 148. 27 Several double stars suspected to belong to a common gravitational system. 1876Newcomb in N. Amer. Rev. CXXIII. 101 Theoretical astronomy is a term somewhat too vague and inclusive; and ‘gravitational astronomy’ somewhat too narrow. 1881Sir R. Ball in Eng. Mech. 17 June 349/1 Modern gravitational astronomers. 1889Chamb. Jrnl. 16 Mar. 163/1 Venus has nearly the same gravitational power as the earth. 1893Sir R. Ball Story of Sun 75 The gravitational method of finding the Sun's distance.
b. Special collocations: gravitational constant: in classical physics, the constant of proportionality in the equation relating the strength of the gravitational attraction between two bodies to their mass and their separation, equal to approx. 6·67 × 10-11 N. m.2 kg.-2 (6·67 × 10-8 dyne cm.2 gm.-2); symbol G; gravitational mass: the mass of a body as measured by the force exerted on it by a gravitational field; cf. inertial mass; gravitational potential: the potential of a gravitational field, the gradient of which at any point is equal in magnitude and direction to the field at that point; gravitational system (of units): a system of units based on a fundamental unit of weight rather than a unit of mass; gravitational unit: a unit the value of which depends upon the value of g, the acceleration due to gravity; formerly called gravitation unit; gravitational water: the water in saturated soil which can drain away under the influence of gravity; gravitational wave: (a) = gravity wave; (b) a periodic variation in gravitational field-strength which is propagated through space (the existence of such waves is not yet established with certainty).
1904Science XIX. 928/2 The adoption of this unit of mass involves a change in the numerical value of the gravitational constant. 1966McGraw-Hill Encycl. Sci. & Technol. VI. 264 Determining the gravitational constant by a suitable experiment is therefore equivalent to ‘weighing the Earth’.
1918A. S. Eddington Rep. Relativity Theory Gravitation i. 11 In astronomy..the masses of heavenly bodies are measured by their gravitational effects; naturally we cannot legitimately apply (7.8) to gravitational mass without a full discussion of the law of gravitation. 1955Sci. Amer. June 32/2 The theory of general relativity was constructed on the basis of a physical observation of the equivalence of inertial and gravitational mass under certain simple circumstances.
1928Newman & Searle Gen. Prop. Matter iii. 59 To move this unit mass from one point to another in the gravitational field would require an expenditure of work against the attraction. The amount of this work..is called the difference in gravitational potential at the points. 1938W. M. Smart Stellar Dynamics ii. 32 The motion of an individual star at any instant will be determined by the gravitational potential of the system. 1971Sci. Amer. May 69/1 Light emitted from such an object would have to overcome an immense gravitational potential and would be red-shifted just as it is in quasars.
1888Proc. Physical Soc. X. 41 To find J in the metre-kilogram-second gravitational system, when it is given in the British gravitational system. 1899W. Watson Text-bk. Physics i. x. 85 Such a system of units is called a gravitational system, and it is this system which is almost exclusively used by engineers. 1966Kaye & Laby Tables of Physical & Chem. Constants (ed. 13) 6 It is convenient to distinguish the basic units of force in gravitational systems from the basic units of mass in other systems by using the symbols kgf for the kilogramme-force and lbf for the pound-force.
1896Nichols & Franklin Elem. Physics I. iii. 31 (heading) Gravitational units of force. 1923H. Moore Textbk. Interm. Physics viii. 67 The English gravitational unit of power is one foot-pound per second. 1954Amer. Jrnl. Physics XXII. 293/2 The gravitational unit of force..is related to the weight of the standard object.
[1897L. J. Briggs in U.S. Bur. of Soils Bull. No. 10, 6 The water contained in a soil may be considered to be of three kinds—gravitation water, capillary water, and hydroscopic water.] 1907C. W. Burkett Soils iv. 40 Three kinds of water are present in soils: gravitational water, capillary water, and hydroscopic water. Immediately after a rain, gravitational water, or that which will move under the influence of gravity, is present in the soil. 1917Mosier & Gustafson Soil Physics & Management xvii. 217 The movement of gravitational water down⁓ward through the soil by the force of gravity is called percolation. 1960Teuscher & Adler Soil & its Fertility vii. 85 Gravitational water is of next to no importance for plant growth.
1899W. Watson Text-bk. Physics iii. i. 345 The large waves seen on the surface of the sea are well-known examples of gravitational waves. 1941B. Haurwitz Dynamic Meteorol. xiv. 276 (heading) Wave motion at the free surface of a single layer. Gravitational waves. 1963Meteorol. Gloss. (Met. Office) 120 Gravity wave, a type of wave, also referred to as a gravitational wave, in which the controlling forces are gravity and buoyancy. 1906E. E. Fournier d'Albe Electron Theory x. 191 If we had any means of creating or destroying matter, we could produce gravitational waves of infinite wave⁓length. 1922A. S. Eddington in Proc. R. Soc. A. CII. 278 The chief point of practical interest in the problem of the spinning rod is the question whether its energy is gradually carried away by the gravitational waves which are created, so that the rotation would slow down. 1937Einstein & Rosen in Jrnl. Franklin Inst. CCXXIII. 43 The approximate method of integration of the gravitational equations of the general relativity theory leads to the existence of gravitational waves. 1970Sci. Amer. 58/3 Einstein's general theory of relativity predicts that gravitational waves should be produced by matter that is accelerating with respect to the observer. 1971Nature 15 Jan. 185/2 Weber has..presented a plausible case for believing that his detectors may indeed have monitored frequent and sharply pulsed gravitational waves, which seem to be emanating from the centre of our galaxy.
Hence graviˈtationally adv., by gravitation.
1887Sir W. Thomson Sun's Heat in Gd. Words 150 Pieces of matter gravitationally attracted together. 1935Discovery Dec. 352/2 Meteorites are gravitationally drawn towards the Earth. 1965J. D. North Meas. of Universe 417 Using Whittaker's and McCrea's idea of gravitational mass..and restricting his attention to what he termed a ‘gravitationally steady-state’ in which σ is held to a constant value, McVittie found [etc.]. 1968R. A. Lyttleton Myst. Solar Syst. ii. 77 The requisite pressure arises gravitationally.
Add:[b.] gravitational lens Astron., a region of space containing a massive body whose gravitational field affects electromagnetic radiation passing through it in a manner similar to a lens.
1937Astrophysical Jrnl. LXXXVI. 237 (heading) Nebulae as gravitational lenses. 1968Science 18 Oct. 348 In some instances the foreground galaxy will act as a gravitational lens and produce distorted and (in brightness) greatly amplified images of the galaxy behind it. 1979Nature 8 Nov. 183/1 The amazing similarities between these two objects have led to speculations that the image of a single QSO was being split by a gravitational lens in the line of sight. 1987New Scientist 2 July 26/1 The discovery of a companion object close to the supernova discovered earlier this year has caused a flurry of activity among theorists... The most tantalising possibility is that we are seeing the effect of a gravitational lens, a black hole with a mass of a hundred thousand Suns, lying half way between our Galaxy and the supernova. |