Hypothesis Of Motion Research Articles

Eta carinae nebulosities in 1963

The purpose of this note is to give further information regarding the positions of some condensations around η Carinae in 1963, an epoch not yet considered in the literature. The new information is unable to confirm the deceleration hypothesis of theeir motion.

Motion of the Earth's inner core and related variations of polar motion and the rotational velocity

AbstractCorrelations between the geomagnetic field parameters and polar motion were explained using the hypothesis of an inner core motion. For a number of periodic constituents of both phenomena it could be proved that this model works well. Secular variations of polar motion caused by inner core dynamics are in the same order of magnitude as the secular variation of the pole derived from pole coordinates of the International Latitude Service (ILS).

Directly forced oscillations of an inverted pendulum

Directly forced, symmetric oscillations of an inverted, lightly damped pendulum are predicted analytically on the hypothesis of sinusoidal motion in a frequency interval terminated by turning-point and symmetry-breaking bifurcations. The predictions are confirmed by numerical simulation.

Uniqueness of the Friedmann-Lemaître-Robertson-Walker universes

We consider spacetimes with a perfect fluid distribution characterized by the energy density $\ensuremath{\mu}$, pressure $p$, charge density $\ensuremath{\zeta}$, and an equation of state $p=p(\ensuremath{\mu})$, or $p\ensuremath{\equiv}0$. It is shown that the only nonstatic isotropic solution of the Einstein-Maxwell equations where the contraction or expansion of the matter is shear free and the equation of state is physically reasonable is the Friedmann-Lema\^{\i}tre-Robertson-Walker class of solutions. Moreover, this conclusion holds for neutral matter even when the assumption of isotropy is replaced by the weaker hypothesis of irrotational motion.

Étude cinématique de la galaxie barrée NGC 5383

We present some observational results derived from plates taken with the nebular spectrograph at the 1.93-m telescope of the Observatoire de Haute Provence. The dispersion is 35 A mm−1 and the resolution is 85″ per mm. Radial velocities were measured at different points in the nucleus and in the bar. The nucleus is composed of two elements, of 5″ and 12″ diameter, inside a ring of radius 2 kpc. Radial velocities around the ring show a well-defined sinusoid with a maximum displaced about 15° from that predicted from the geometry of the outer parts of the galaxy. We can explain this displacement by a contraction velocity of 43 km s−1. In the bar the kinematics is quite complex. The slit position (roughly aligned with the bar) was slightly different for each of the four plates taken. For those which bisect the nucleus the velocity field is symmetric, with a sharp discontinuity of 50 km s−1 between the nucleus and the bar. The maximum velocity is not reached in our field of observation. Solid body rotation cannot be accepted. Spectra along the edge of the nucleus provides evidence for transverse motions in the bar of 100 km s−1 at 4 kpc from the center. The rotation curve is drawn; in the hypothesis of a radial motion in the bar we have calculated the distribution of mass according to the method of Burbidge and Prendergast inside a 14 kpc radius; the mass is 1010 M ⊙. The iso-intensity tracings clearly show the presence of the two nuclear components, the absence of [Nii] emission on the north-west side of the bar and the absence of Hα in the south-west side. The ratio Hα/[Nii] between 2 and 5 at several spots indicates that Hii regions are highly excited in the nucleus and at the extreme end of the bar. The region of the bar where the ratio is less than 1 suggests high excitation by collision of energetic particle perhaps coming from the nucleus.

Devonian geology of Banks Island, Arctic Canada, and its bearing on the tectonic development of the circum-Arctic region

New information, predominantly from the subsurface, shows that the Devonian rocks of Banks Island comprise four units: a shelf carbonate formation (Siegenian? to Eifelian), a basin-slope calcareous shale (Emsian to late Givetian), a basinal cherry shale (Emsian to Eifelian), and a predominantly deltaic clastic unit (Givetian to Famennian). Paleogeographic reconstructions show southern Banks Island as part of the stable shelf in Early Devonian time. During Middle Devonian time, subsidence took place, and basinal conditions encroached on the shelf from the north. The deep basin is considered to be part of Hazen Trough, which probably was connected with Richardson Trough of northern Yukon. Subsequent tectonic events have left the Devonian rocks of Banks Island relatively undisturbed, in comparison with those of the Parry Islands to the north. Evidence of subduction and plate collision — such as strong deformation, the development of orogenic welts, and the production of thick, locally derived clastic wedges — is absent in Banks Island, in contrast to areas such as northern Ellesmere Island and northern Alaska. Therefore, if plate movements did take place in the Arctic during Devonian time, Banks Island may have lain opposite an embayment in the advancing plate, resulting in incomplete suturing, as described by Dewey and Burke. However, no satisfactory hypothesis of plate motion in the Arctic has yet been developed, in spite of many attempts.

The Peculiar Star 17 Leporis

view Abstract Citations (10) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Peculiar Star 17 Leporis Widing, Kenneth G. Abstract New photometric and spectroscopic materials suggest that the A-type main-sequence star investigated by Struve is accompanied by a subgiant M secondary filling its inner contact surface. The slow and irregular light variation amounting to only 0.07 mag. in the yellow is attributed to the activity of the M star, and the observed colors are attributed to the composite nature of the system. A total of 105 lines and band heads belonging to the spectrum is found in the Ha region. The radial velocity of this spectrum is variable with an amplitude of more than 40 km/sec. Although the observations are few, the velocity variation is not inconsistent with the hypothesis of orbital motion in a period of 276 days. Publication: The Astrophysical Journal Pub Date: January 1966 DOI: 10.1086/148482 Bibcode: 1966ApJ...143..121W full text sources ADS | data products SIMBAD (7) GCPD (1)

Motion of the Storm-D Regions

W. R. PIGGOTT1 has reported coherent variations with longitude which he interprets as motion of the “storm-D regions” once around the earth in 48 hr. This result is based on the data of about three years from each of six vertical-incidence ionospheric stations. Work at the National Bureau of Standards, however, based on ionospheric data tabulations from seventeen stations for the four years, 1949–52, does not support the hypothesis of coherent motion of such regions.

On the spinless rectilinear motion of a uniformly and rigidly electrified sphere—II

This paper constitutes the second instalment of a series of investigations foreshadowed in paper I; its object is to obtain a rigorous and exact expression for the total mechanical reaction on the moving sphere due to its own field and to deduce the complete equation of motion. With the exception of some papers on the perfectly conducting sphere by Searle, Sommerfeld, G. W. Walker, and Livens, which are of purely academic interest in so far as they do not appear to have been applied to concrete problems, nothing seems to have been done in this field of knowledge beyond the work of Abraham on the perfectly conducting sphere and that of Lorentz on the deformable Heaviside spheroid, both only for quasi-stationary motion. Their work, as well as my own previous work based upon it, is only approximate and hypothetical, for it is based fundamentally on series for the potentials and electric and magnetic forces, whose convergence has never been established and only the two first terms of which have ever used, viz., the principal term defining the electromagnetic mass and the second representing the pressure due to radiation. Consequently this approximate electrodynamics, based on the hypothesis of quasi-stationary motion, has led to contradictions with experiment, particularly as regards the behaviour of β-particles near atomic nuclei. Only a rigorous and exact electrodynamics can reasonably be expected to explain such phenomena, but, unfortunately, we find ourselves on the horns of a dilemma: to develop such an electrodynamics without restrictions either as to the nature of the electrified system or as to the character of its motion seems to be impracticable in the present state of analysis. It happens that the method developed in the previous paper (I) leads to a rigorous and exact expression for the total mechanical reaction on a uniformly and rigidly electrified sphere due to its own electromagnetic field without any other restriction on its motion beyond that which secures that the speed of every one of its elements shall be less than that of light—indeed, this restriction is only imposed to simplify the analysis and is not serious in view of relativity considerations. Neither the perfectly conducting sphere of Abraham nor the deformable Heaviside spheroid of Lorentz lends itself so easily to analysis, but I have hopes of being able to extend some of the results to the case of the Heaviside spheroid. As a beginning the present paper treats only of the rectilinear motion without spin, in which every element of the sphere at any one instant for the fixed observer has the same velocity as the centre, but this velocity can vary with the time according to any law, not necessarily the same law for all time, provided only that it never exceeds the velocity of light. The case of curvilinear motion and the effect of spin will be treated in future papers. In spite of the restricted character of the motion and the very specialized and artificial nature of the electrified system, some surprising results are obtained which cast considerable doubt on some of the conclusions generally accepted as certain in classical electrodynamics.

On the formation of water waves by wind

It is well known that in certain circumstances a type of instability may arise at the surface of separation of two fluids when there is a finite difference between the velocities on the two sides of the surface. Some disturbances of the surface, of simple harmonic type, may increase exponentially in amplitude until the customary simplifying assumption, that the terms of the second degree in the displacements from the undisturbed state can be ignored, breaks down. One would naturally expect that in the case, for instance, of a wind blowing over the surface of water, waves would be first formed when the velocity of the wind is just great enough to make one particular type of wave grow; thus the critical wind velocity and the wave-length of the waves first formed will constitute checks on any theory of wave formation. The problem for frictionless fluids has been solved by Lord Kelvin, subject to the restriction that the disturbances considered are two-dimensional, no horizontal displacement occurring across the relative velocity of the fluids. Since, however, the possible initial deformations of a horizontal surface will not as a rule satisfy this condition, an investigation of the growth or decay of deformations of other types is desirable. 1. Hypothesis of Irrotational Motion . Let the two fluids be incompressible (a legitimate approximation so long as the wave velocity is small compared with that of sound in either fluid) and of great vertical extent. Let the origin be in the undisturbed position of the surface of separation and the axis of z vertically upwards. Let ζ be the elevation of the surface, and suppose the two fluids to have initially velocities U and U' parallel to the axis of x , accents referring to the upper fluid. Let the densities of the fluids be respectively ρ and ρ', and the velocity potentials in them Ф and Ф' . Let the operators ∂/∂ t , ∂/∂ x , ∂/∂ y , ∂/∂ z be denoted by σ, p , q , and ϑ respectively. Putting r 2 for — ( p 2 + q 2 we see that ∇ 2 Φ = 0 (1) is equivalent to (ϑ 2 — r 2 ) Ф = 0, (2) whence Ф = U x + e rz A, (3) where A is a function of x and y , determined by the value of Ф where z is zero.

On the north polar distances of the principal fixed stars

The author observes, that of the recent catalogues that have been formed of the principal fixed stars, two, those of Dublin and Greenwich, agree very exactly. That of M. Bessel differs considerably; but the differences are such that they would agree by a modification of the co-efficients of refraction employed for correcting the observations. Mr. Pond, he says, has applied the refractions of Bradley to the instrument of Dublin; he himself thinks it more safe to determine the refraction for each place from its own instruments; and he objects to the reasoning by which Mr. Pond has endeavoured to prove the existence of a flexure in the tube of the instrument of Dublin. Dr. Brinkley makes the mean difference of the stars of Greenwich and Dublin for 1813 only a few tenths of a second; for 1823, still less. Neither the Dublin Catalogue, nor any other more extensive comparison, affords, in his opinion, a confirmation of the hypothesis of a general southern motion, which he is therefore inclined to attribute principally to a slight inaccuracy of the Greenwich Catalogue for 1813.

An accompt of some books. - I. An essay about the origine and vertues of gems; by the Honourable Robert Boyl Esquire, Fellow of the R. Society. printed at London, 1672. in 80. - II. Johannis Swammerdami M. D. uteri muliebris fabrica; unà cum methodo nova cavitates corporis ita præparandi, ut suam semper genuinam faciem servent. Lugduni Batav. 1672. in

An accompt of some books. - I. An essay about the origine and vertues of gems; by the Honourable Robert Boyl Esquire, Fellow of the R. Society. printed at London, 1672. in 80. - II. Johannis Swammerdami M. D. uteri muliebris fabrica; unà cum methodo nova cavitates corporis ita præparandi, ut suam semper genuinam faciem servent. Lugduni Batav. 1672. in 4º. - III. Three letters of Jo. Dominicus Cassinus, concerning his hypothesis of the suns motion, and his doctrine of refractions; printed at Bononia in 4º. - IV. Dr. Richard Sharrock’s history of the propagation and improvement of vegetables; by the concurrence of art and nature. The 2d edition much enlarged. Oxford, 1672. in 8º. The design of the Noble Author of this excellent Treatise being, to propose and historically to illustrate therein some conjectures of his about the Consistence of the Matter of Precious Stones, and the Subjects wherein their chief vertues reside; he comprises the substance of all in these two particulars.

Extract of a letter, lately written from Rome, touching the late comet, and a new one

I cannot enough wonder at the strange agreement of the thoughts of that acute French gentleman, Monfieur Auzout,in the hypothesis of comets motion, with mine; and particularly, at that of the tables.