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Pendulum

suspended weight capable of swinging freely from a pivot

A pendulum is a device consisting of a weight suspended from a pivot so that it can swing freely in response to the force of gravity. When a pendulum is displaced sideways from its resting equilibrium position, gravity will accelerate it back toward the equilibrium position. The regular motion of pendulums was used for timekeeping, and was the world's most accurate timekeeping technology until the 1930s. Metaphorically the swing of a pendulum can refer to periodic changes or to time itself.

The history of human thought recalls the swinging of a pendulum which takes centuries to swing. After a long period of slumber comes a moment of awakening. ~ Peter Kropotkin


CONTENT : A - F , G - L , M - R , S - Z , See also , External links

Quotes

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Quotes are arranged alphabetically by author

A - F

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In order that a pendulum may continue to make the same number of oscillations in a given time, it must be shortened as it is carried towards the equator; and the variation of its length in different latitudes affords an accurate measurement of the force of gravity. But the force of gravity has known relation to the figure of the earth, which, therefore, may be determined, by observing the length of the seconds pendulum at different points on its surface. - Sir David Brewster.
  • In order that a pendulum may continue to make the same number of oscillations in a given time, it must be shortened as it is carried towards the equator; and the variation of its length in different latitudes affords an accurate measurement of the force of gravity. But the force of gravity has known relation to the figure of the earth, which, therefore, may be determined, by observing the length of the seconds pendulum at different points on its surface.
  • All the colours look brighter now.
    Everything they say seems to sound new.
    Slipping into tomorrow too quick,
    Yesterday always too good to forget.
    Stop the swing of the pendulum! Let us through!
 
For the better part of my last semester at Garden City High, I constructed a physical pendulum and used it to make a “precision” measurement of gravity.... - Steven Chu.
  • For the better part of my last semester at Garden City High, I constructed a physical pendulum and used it to make a “precision” measurement of gravity. The years of experience building things taught me skills that were directly applicable to the construction of the pendulum. Twenty-five years later, I was to develop a refined version of this measurement using laser-cooled atoms in an atomic fountain interferometer.
  • If it is possible to have a linear unit that depends on no other quantity, it would seem natural to prefer it. Moreover, a mensural unit taken from the earth itself offers another advantage, that of being perfectly analogous to all the real measurements that in ordinary usage are also made upon the earth, such as the distance between two places or the area of some tract, for example. It is far more natural in practice to refer geographical distances to a quadrant of a great circle than to the length of a pendulum.
  • Idiot. Above her head was the only stable point in the cosmos, the only refuge from the damnation of the panta rei, and she guessed it was the Pendulum's business. A moment later the couple went off -- he, trained on some textbook that had blunted his capacity for wonder, she, inert and insensitive to the thrill of the infinite, both oblivious of the awesomeness of their encounter -- their first and last encounter -- with the One, the Ein-Sof, the Ineffable. How could you fail to kneel down before this altar of certitude?”
  • Politics is a pendulum whose swings between anarchy and tyranny are fueled by perpetually rejuvenated illusions.
  • Ideas came with explosive immediacy, like an instant birth. Human thought is like a monstrous pendulum; it keeps swinging from one extreme to the other.
    • Eugene Field, as quoted in As One Mad with Wine and Other Similes (1991) by Elyse Sommer, p. 207

G - L

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  • When young Galileo, then a student at Pisa, noticed one day during divine service a chandelier swinging backwards and forwards, and convinced himself, by counting his pulse, that the duration of the oscillations was independent of the arc through which it moved, who could know that this discovery would eventually put it in our power, by means of the pendulum, to attain an accuracy in the measurement of time till then deemed impossible, and would enable the storm-tossed seaman in the most distant oceans to determine in what degree of longitude he was sailing?
  • I simply state that I'm a product of a versatile mind in a restless generation — with every reason to throw my mind and pen in with the radicals. Even if, deep in my heart, I thought we were all blind atoms in a world as limited as a stroke of a pendulum, I and my sort would struggle against tradition; try, at least, to displace old cants with new ones. I've thought I was right about life at various times, but faith is difficult. One thing I know. If living isn't seeking for the grail it may be a damned amusing game.
 
...He that understands the nature of the Circular Pendulum and Circular Motion, will easily understand the whole ground of this Principle, and will know where to find direction in Nature for the true stating thereof. This I only hint at present to such as have ability and opportunity of prosecuting this Inquiry, and are not wanting of Industry for observing and calculating, wishing heartily such may be found, having myself many other things in hand which I would first complete and therefore cannot so well attend it. But this I durst promise the Undertaker, that he will find all the Great Motions of the World to be influenced by this Principle, and that the true understanding thereof will be the true perfection of Astronomy. - Robert Hooke.
  • I shall explain a System of the World differing in many particulars from any yet known, answering in all things to the common Rules of Mechanical Motions: This depends upon three Suppositions. First, That all Cœlestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers, whereby they attract not only their own parts, and keep them from flying from them, as we may observe the Earth to do, but that they do also attract all the other Cœlestial bodies that are within the sphere of their activity; and consequently that not only the Sun and Moon have an influence upon the body and motion the Earth, and the Earth upon them, but that Mercury also Venus, Mars, Saturn and Jupiter by their attractive powers, have a considerable influence upon its motion in the same manner the corresponding attractive power of the Earth hath a considerable influence upon every one of their motions also. The second supposition is this, That all bodies whatsoever that are put into a direct and simple motion, will continue to move forward in a straight line, till they are by some other effectual powers deflected and bent into a Motion, describing a Circle, Ellipse, or some other more compounded Curve Line. The third supposition is, That these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers. Now what these several degrees are I have not yet experimentally verified; but it is a notion, which if fully prosecuted as it ought to be, will mightily assist the Astronomer to reduce all the Cœlestial Motions to a certain rule, which I doubt will never be done true without it. He that understands the nature of the Circular Pendulum and Circular Motion, will easily understand the whole ground of this Principle, and will know where to find direction in Nature for the true stating thereof. This I only hint at present to such as have ability and opportunity of prosecuting this Inquiry, and are not wanting of Industry for observing and calculating, wishing heartily such may be found, having myself many other things in hand which I would first complete and therefore cannot so well attend it. But this I durst promise the Undertaker, that he will find all the Great Motions of the World to be influenced by this Principle, and that the true understanding thereof will be the true perfection of Astronomy.
  • To all appearance, the phenomena exhibited by the pendulum are not to be accounted for by impact: in fact, it is usually assumed that corresponding phenomena would take place if the earth and the pendulum were situated in an absolute vacuum, and at any conceivable distance from one another. If this be so, it follows that there must be two totally different kinds of causes of motion: the one impact—a vera causa [true cause], of which, to all appearance, we have constant experience; the other, attractive or repulsive 'force'—a metaphysical entity which is physically inconceivable.
 
The length of the pendulum and that of the meridian are the two principal means offered by Nature for fixing the unity of linear measurements. Both being independent of moral revolutions, they can undergo no detectable alteration short of enormous changes in the physical constitution of the earth.... - Laplace.
  • The length of the pendulum and that of the meridian are the two principal means offered by Nature for fixing the unity of linear measurements. Both being independent of moral revolutions, they can undergo no detectable alteration short of enormous changes in the physical constitution of the earth. The first method is easily applicable, but has the disadvantage of making the measurement of distance depend on two elements that are heterogeneous to it, gravity and time, the division of [the latter of] which, moreover, is arbitrary. It was decided, therefore, to adopt the second method, which appears to have been employed in early antiquity, so natural is it for man to relate the units of distance by which travels to the dimensions of the globe that he inhabits. In moving about this globe, he may thus know by the simple denomination of the distance the proportion it bears to the entire circumference of the earth. This has the further advantage of making nautical and celestial measurements correspond. The navigator often needs to determine, one from the other, the distance he has traversed and [the length of] the celestial arc lying between the zenith at this point of departure and that at his destination.It is important, therefore, that one of these magnitudes should be the expression of the other, with no difference except in the units. But to that end, the fundamental linear unit must be an aliquot part of the terrestrial meridian, which corresponds to one of the divisions of the curcumferance.Thus the choice of the meter came down to that of unity of angles.
    • Laplace in: "Science and Polity in France: The End of the Old Regime", p. 241.
 
The first pendulam clock. - The person who observes a clock, sees in it not only the pendulum swinging to and fro, and the dial-plate, and the hands moving, for a child can see all this; but he sees also the parts of the clock, and in what connection the suspended weight stands to the wheel-work, and the pendulum to the moving hands. - Baron von Liebig.
  • The person who observes a clock, sees in it not only the pendulum swinging to and fro, and the dial-plate, and the hands moving, for a child can see all this; but he sees also the parts of the clock, and in what connection the suspended weight stands to the wheel-work, and the pendulum to the moving hands.

M - R

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  • Time is a valuable thing
    Watch it fly by as the pendulum swings
    Watch it count down to the end of the day
    The clock ticks life away
  • Pendulums have been carried about the world and the times of swing of the same pendulum have been exactly measured in widely different latitudes. The results of these measurements show quite conclusively that the weight of the bob of a given pendulum increases as we travel polewards from the equator, and we may thus described the change. If we had a perfect pendulum clock compensated for temperature change and barometer change (for if the density of the air changes, so does the effect on the buoyancy of the pendulum change), then on removal from the equator to this country it would gain about 130 seconds a day, and on removal from the equator to the pole it would gain about 216 seconds a day.

S - Z

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  • Imagine you want to know the sex of your unborn child. There are several approaches. You could, for example, do what the late film star ... Cary Grant did before he was an actor: In a carnival or fair or consulting room, you suspend a watch or a plumb bob above the abdomen of the expectant mother; if it swings left-right it's a boy, and if it swings forward-back it's a girl. The method works one time in two. Of course he was out of there before the baby was born, so he never heard from customers who complained he got it wrong.... But if you really want to know, then you go to amniocentesis, or to sonograms; and there your chance of being right is 99 out of 100. ... If you really want to know, you go to science.
  • For FRICTION is inevitable because the Universe is FULL of God's works.
    For the PERPETUAL MOTION is in all works of Almighty GOD.
    For it is not so in the engines of man, which are made of dead materials, neither indeed can be.
    For the Moment of bodies, as it is used, is a false term—bless God ye Speakers on the Fifth of November.
    For Time and Weight are by their several estimates.
    For I bless GOD in the discovery of the LONGITUDE direct by the means of GLADWICK.
    For the motion of the PENDULUM is the longest in that it parries resistance.
    For the WEDDING GARMENTS of all men are prepared in the SUN against the day of acceptation.
    For the wedding Garments of all women are prepared in the MOON against the day of their purification.
    For CHASTITY is the key of knowledge as in Esdras, Sir Isaac Newton & now, God be praised, in me.
    For Newton nevertheless is more of error than of the truth, but I am of the WORD of GOD.
  • Our advanced and fashionable thinkers are, naturally, out on a wide swing of the pendulum, away from the previous swing of the pendulum.... They seem to have an un-argue-out-able position, as is the manner of sophists, but this is no guarantee that they are right.
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