| 释义 |
centripetal, a.|sɛnˈtrɪpɪtəl|
[f. mod.L. centripet-us (Newton) centre-seeking + -al1. With mod.L. centrifugus, centripetus, cf. Isid. xii. viii. 9 ‘musca lucipeta, blatta lucifuga est’; heredipeta, lucripeta also occur in L. Cf. mod.F. centripète.]
1. Tending toward the centre; the opposite of centrifugal.
a. centripetal force: a force which draws or impels a body toward some point as a centre, and thus acts as a counterpoise to the centrifugal tendency in circular motion; for this the name centripetal tendency is substituted by some.
[1687Newton Principia Defin. v, Vim conatui illi contrariam..Centripetam appello.] 1709Tatler No. 43 ⁋7 Thus the Tangential and Centripetal Forces, by their Counter-struggle, make the Celestial Bodies describe an exact Ellipsis. 1764Reid Inquiry ii. §9 Centripetal force is put for the cause, which we conceive to be some power or virtue in the centre or central body. 1841–4[see centrifugal 1]. 1868Lockyer Elem. Astron. 306 Were the centrifugal tendency to cease, the centripetal force would be uncontrolled, and the body would fall upon the attracting mass.
b. fig. and transf.
a1711Ken Sion Wks. 1721 IV. 419 They Unwing'd, as swiftly flew the spacious way, By their centripetal connat'ral Force, To their Triune, co-amiable Source. a1763Shenstone Ess. 112 Indolence is a kind of centripetal force. 1870Gladstone Glean. iv. vi. 202 While centripetal and centrifugal forces are thus engaged in mortal tug.
2. Applied to machines or parts of mechanism which employ centripetal action: as centripetal press, centripetal pump.
1874Knight Dict. Mech., Centripetal pump..in one form it is the exact converse of the Barker Mill.
3. Bot. Tending or developing from without toward the centre. centripetal inflorescence, that in which the lowest or outermost flowers blossom first, as in spikes and umbels; also called indeterminate or indefinite.
1870Hooker Stud. Flora 184 Compositæ..Inflorescence a centripetal head of many small flowers. 1880Gray Struct. Bot. v. 145 The Indefinite or Indeterminate type of inflorescence has been called Centripetal, because..the evolution is seen to proceed from circumference to centre. 1882Vines Sachs' Bot. 536 The acropetal or centripetal order of succession of the floral leaves.
4. Biol.
a. Proceeding from the exterior to the interior or centre.
b. Of nerves: Conveying an impulse from the periphery to the ‘centre’; afferent.
1836Todd Cycl. Anat. I. 763/1 The law of centripetal development. 1855Owen Skel. & Teeth 131 As the centripetal calcification proceeds, the caps are converted into horn-shaped cones. 1877Roberts Handbk. Med. (ed. 3) I. 52 The centripetal or sensory nerves. |