Center-of-mass operators and covariant decomposition of the total angular momentum

1967 ◽  
Vol 47 (2) ◽  
pp. 299-318 ◽  
Author(s):  
G. Lugarini ◽  
M. Pauri
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Center Of Mass ◽  
Covariant Decomposition

Complete Shaking Force and Shaking Moment Balancing of Link Mechanisms Using Balancing Idler Loops

1982 ◽  
Vol 104 (2) ◽  
pp. 482-493 ◽  
Author(s):  
Cemil Bagci
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Center Of Mass ◽  
Numerical Example ◽  
Shaking Moment

A method for completely balancing the shaking forces and shaking moments in mechanisms is presented. The method introduces shaking moment balancing idler parallelogram loop (or loops) which transfers the motion of a coupler link to a shaft on the frame of the mechanism, where the rotary balancers balance the shaking moment. The complete balancing of a mechanism is accomplished by maintaining the total center of mass of the mechanism stationary meanwhile achieving that the total angular momentum of the moving links of the mechanism vanishes. Positioning of the idler loops is illustrated for a series of multiloop mechanisms. Theorems on the complete balancing of shaking forces and shaking moments in mechanisms are established. Design equations for completely balancing some single and multiloop mechanisms are given. A numerical example is included.

Takeoff Mechanics of the Double Backward Somersault

1990 ◽  
Vol 6 (2) ◽  
pp. 177-186 ◽  
Author(s):  
Inseong Hwang ◽  
Gukung Seo ◽  
Zhi Cheng Liu
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Dominant Role ◽  
Center Of Mass ◽  
Velocity Curve ◽  
The Other ◽  
Transverse Axis ◽  
Angular Momenta ◽  
Total Body ◽  
Direction Opposite

This study examined the biomechanical profiles of the takeoff phase of double backward somersaults in three flight positions: seven layout double backward somersaults (L), seven twisting double backward somersaults (TW), and seven tucked double backward somersaults (TDB). Selected kinematic variables and angular momenta were calculated in order to compare the differences resulting from different aerial maneuvers. The amount of total body angular momentum about the transverse axis through the gymnasts' center of mass progressively increased from TDB to TW to L. The gymnasts performing the skill in the layout position tried to minimize the angle of block in a direction opposite the intended motion by maximizing the angle of touchdown and takeoff. In so doing, the horizontal velocity center-of-mass curve of the L showed a slowly decreasing curve compared with those of the other two somersaults while the vertical velocity curve of the L increased more slowly than the other curves during the takeoff phase. In all cases the legs played the dominant role in contributing to total angular momentum during takeoff.

Angular Momentum in Multiple Rotation Nontwisting Platform Dives

1986 ◽  
Vol 2 (2) ◽  
pp. 78-87 ◽  
Author(s):  
Joseph Hamill ◽  
Mark D. Ricard ◽  
Dennis M. Golden
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Center Of Mass ◽  
Transverse Axis ◽  
Flight Phase ◽  
Local Contribution ◽  
Percent Contribution ◽  
Total Body

A study was undertaken to investigate the changes in total body angular momentum about a transverse axis through the center of mass that occurred as the rotational requirement in the four categories of nontwisting platform dives was increased. Three skilled subjects were filmed performing dives in the pike position, with increases in rotation in each of the four categories. Angular momentum was calculated from the initiation of the dive until the diver reached the peak of his trajectory after takeoff. In all categories of dives, the constant, flight phase total body angular momentum increased as a function of rotational requirement. Increases in the angular momentum at takeoff due to increases in the rotational requirement ranged from a factor of 3.61 times in the forward category of dives to 1.52 times in the inward category. It was found that the remote contribution of angular momentum contributed from 81 to 89% of the total body angular momentum. The trunk accounted for 80 to 90% of the local contribution. In all categories of dives except the forward 1/2 pike somersault, the remote percent contribution of the arms was the largest of all segments, ranging from 38 to 74% of the total angular momentum.

CENTER OF MASS AND SPIN FOR AXIALLY SYMMETRIC SPACETIMES

2011 ◽  
Vol 20 (05) ◽  
pp. 717-728 ◽  
Author(s):  
CARLOS KOZAMEH ◽  
RAUL ORTEGA ◽  
TERESITA ROJAS
Keyword(s):  
Angular Momentum ◽  
Gravitational Radiation ◽  
Total Angular Momentum ◽  
Equations Of Motion ◽  
Center Of Mass ◽  
Axially Symmetric ◽  
Symmetric Spacetimes ◽  
Intrinsic Angular Momentum

We give equations of motion for the center of mass and intrinsic angular momentum of axially symmetric sources that emit gravitational radiation. This symmetry is used to uniquely define the notion of total angular momentum. The center of mass then singles out the intrinsic angular momentum of the system.

scholarly journals Infrared effects in the late stages of black hole evaporation

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Éanna É. Flanagan
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Center Of Mass ◽  
Planck Scale ◽  
Black Hole Mass ◽  
Order Unity ◽  
Intrinsic Angular Momentum ◽  
Hole Position ◽  
Late Stages ◽  
Shear Tensor

Abstract As a black hole evaporates, each outgoing Hawking quantum carries away some of the black holes asymptotic charges associated with the extended Bondi-Metzner-Sachs group. These include the Poincaré charges of energy, linear momentum, intrinsic angular momentum, and orbital angular momentum or center-of-mass charge, as well as extensions of these quantities associated with supertranslations and super-Lorentz transformations, namely supermomentum, superspin and super center-of-mass charges (also known as soft hair). Since each emitted quantum has fluctuations that are of order unity, fluctuations in the black hole’s charges grow over the course of the evaporation. We estimate the scale of these fluctuations using a simple model. The results are, in Planck units: (i) The black hole position has a uncertainty of $$ \sim {M}_i^2 $$ ∼ M i 2 at late times, where Mi is the initial mass (previously found by Page). (ii) The black hole mass M has an uncertainty of order the mass M itself at the epoch when M ∼ $$ {M}_i^{2/3} $$ M i 2 / 3 , well before the Planck scale is reached. Correspondingly, the time at which the evaporation ends has an uncertainty of order $$ \sim {M}_i^2 $$ ∼ M i 2 . (iii) The supermomentum and superspin charges are not independent but are determined from the Poincaré charges and the super center-of-mass charges. (iv) The supertranslation that characterizes the super center-of-mass charges has fluctuations at multipole orders l of order unity that are of order unity in Planck units. At large l, there is a power law spectrum of fluctuations that extends up to l ∼ $$ {M}_i^2/M $$ M i 2 / M , beyond which the fluctuations fall off exponentially, with corresponding total rms shear tensor fluctuations ∼ MiM−3/2.

scholarly journals Total Angular Momentum Dichroism of the Terahertz Vortex Beams at the Antiferromagnetic Resonances

2021 ◽  
Vol 126 (15) ◽  
Author(s):  
A. A. Sirenko ◽  
P. Marsik ◽  
L. Bugnon ◽  
M. Soulier ◽  
C. Bernhard ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Vortex Beams

Determination of the total angular momentum of a paraxial beam

2008 ◽  
Vol 78 (5) ◽  
Author(s):  
Gabriel Molina-Terriza
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum

The continuation in total angular momentum of partial-wave scattering amplitudes for particles with spin

1963 ◽  
Vol 25 (3) ◽  
pp. 325-339 ◽  
Author(s):  
Francesco Calogero ◽  
John M Charap ◽  
Euan J Squires
Keyword(s):  
Angular Momentum ◽  
Scattering Amplitudes ◽  
Partial Wave ◽  
Wave Scattering ◽  
Total Angular Momentum
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