What is "centripetal force"

Force \Force\, n. [F. force, LL. forcia, fortia, fr. L. fortis strong. See Fort, n.]

1. Capacity of exercising an influence or producing an effect; strength or energy of body or mind; active power; vigor; might; often, an unusual degree of strength or energy; especially, power to persuade, or convince, or impose obligation; pertinency; validity; special signification; as, the force of an appeal, an argument, a contract, or a term.

   He was, in the full force of the words, a good man.
   --Macaulay.

2. Power exerted against will or consent; compulsory power; violence; coercion; as, by force of arms; to take by force.

   Which now they hold by force, and not by right.
   --Shak.

3. Strength or power for war; hence, a body of land or naval combatants, with their appurtenances, ready for action; -- an armament; troops; warlike array; -- often in the plural; hence, a body of men prepared for action in other ways; as, the laboring force of a plantation; the armed forces.

   Is Lucius general of the forces?
   --Shak.

4. (Law)

   1. Strength or power exercised without law, or contrary to law, upon persons or things; violence.

   2. Validity; efficacy.
      --Burrill.

5. (Physics) Any action between two bodies which changes, or tends to change, their relative condition as to rest or motion; or, more generally, which changes, or tends to change, any physical relation between them, whether mechanical, thermal, chemical, electrical, magnetic, or of any other kind; as, the force of gravity; cohesive force; centrifugal force.

   Animal force (Physiol.), muscular force or energy.

   Catabiotic force [Gr. ? down (intens.) + ? life.] (Biol.), the influence exerted by living structures on adjoining cells, by which the latter are developed in harmony with the primary structures.

   Centrifugal force, Centripetal force, Coercive force, etc. See under Centrifugal, Centripetal, etc.

   Composition of forces, Correlation of forces, etc. See under Composition, Correlation, etc.

   Force and arms [trans. of L. vi et armis] (Law), an expression in old indictments, signifying violence.

   In force, or Of force, of unimpaired efficacy; valid; of full virtue; not suspended or reversed. ``A testament is of force after men are dead.''
   --Heb. ix. 17.

   Metabolic force (Physiol.), the influence which causes and controls the metabolism of the body.

   No force, no matter of urgency or consequence; no account; hence, to do no force, to make no account of; not to heed. [Obs.]
   --Chaucer.

   Of force, of necessity; unavoidably; imperatively. ``Good reasons must, of force, give place to better.''
   --Shak.

   Plastic force (Physiol.), the force which presumably acts in the growth and repair of the tissues.

   Vital force (Physiol.), that force or power which is inherent in organization; that form of energy which is the cause of the vital phenomena of the body, as distinguished from the physical forces generally known.

   Syn: Strength; vigor; might; energy; stress; vehemence; violence; compulsion; coaction; constraint; coercion.

   Usage: Force, Strength. Strength looks rather to power as an inward capability or energy. Thus we speak of the strength of timber, bodily strength, mental strength, strength of emotion, etc. Force, on the other hand, looks more to the outward; as, the force of gravitation, force of circumstances, force of habit, etc. We do, indeed, speak of strength of will and force of will; but even here the former may lean toward the internal tenacity of purpose, and the latter toward the outward expression of it in action. But, though the two words do in a few cases touch thus closely on each other, there is, on the whole, a marked distinction in our use of force and strength. ``Force is the name given, in mechanical science, to whatever produces, or can produce, motion.''
   --Nichol.

   Thy tears are of no force to mollify This flinty man.
   --Heywood.

   More huge in strength than wise in works he was.
   --Spenser.

   Adam and first matron Eve Had ended now their orisons, and found Strength added from above, new hope to spring Out of despair.
   --Milton.

Centripetal \Cen*trip"e*tal\, a. [L. centrum center + petere to move toward.]

1. Tending, or causing, to approach the center.

2. (Bot.)

   1. Expanding first at the base of the inflorescence, and proceeding in order towards the summit.

   2. Having the radicle turned toward the axis of the fruit, as some embryos.

3. Progressing by changes from the exterior of a thing toward its center; as, the centripetal calcification of a bone.
   --R. Owen.

   Centripetal force (Mech.), a force whose direction is towards a center, as in case of a planet revolving round the sun, the center of the system, See Centrifugal force, under Centrifugal.

   Centripetal impression (Physiol.), an impression (sensory) transmitted by an afferent nerve from the exterior of the body inwards, to the central organ.

n. (context physics English) The force on a rotating or orbiting body in the direction of the centre of rotation.

n. the inward force on a body moving in a curved path around another body [ant: centrifugal force]

A centripetal force (from Latin centrum, "center" and petere, "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre". In Newtonian mechanics, gravity provides the centripetal force responsible for astronomical orbits.

One common example involving centripetal force is the case in which a body moves with uniform speed along a circular path. The centripetal force is directed at right angles to the motion and also along the radius towards the centre of the circular path. The mathematical description was derived in 1659 by the Dutch physicist Christiaan Huygens.