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.

The contribution of valence quarks in the nucleon GE and GM

2019 ◽  
Vol 34 (27) ◽  
pp. 1950148
Author(s):  
Negin Sattary Nikkhoo ◽  
Mohammad Reza Shojaei
Keyword(s):  
Experimental Data ◽  
Angular Momentum ◽  
Form Factor ◽  
Total Angular Momentum ◽  
Form Factors ◽  
Distribution Functions ◽  
The Other ◽  
Parton Distribution Functions ◽  
Nucleon Electromagnetic Form Factor ◽  
Elastic Form

The goal of this paper is to extract the flavor decomposition of nucleon electromagnetic form factor using the modified Gaussian and extended Regge ansatzes in the GPDs. We consider the CJ15 and JR09 parton distribution functions for both of these ansatzes in calculating the nucleon elastic form factors. Our results are compared with experimental data in the range [Formula: see text] 4-momentum transfers. Also, we calculate the total angular momentum carried by quarks, the gravitational form factors, and the transverse gravitational density for quarks of the nucleon. In the end, our results are compared with the other studies.

scholarly journals Calibration of the angular momenta of the minor planets in the solar system

2019 ◽  
Vol 630 ◽  
pp. A68 ◽  
Author(s):  
Jian Li ◽  
Zhihong Jeff Xia ◽  
Liyong Zhou
Keyword(s):  
Angular Momentum ◽  
Solar System ◽  
Total Angular Momentum ◽  
Physical Parameters ◽  
Minor Planets ◽  
The Sun ◽  
Relative Angle ◽  
Angular Momenta ◽  
Dwarf Planets ◽  
Invariable Plane

Aims. We aim to determine the relative angle between the total angular momentum of the minor planets and that of the Sun-planets system, and to improve the orientation of the invariable plane of the solar system. Methods. By utilizing physical parameters available in public domain archives, we assigned reasonable masses to 718 041 minor planets throughout the solar system, including near-Earth objects, main belt asteroids, Jupiter trojans, trans-Neptunian objects, scattered-disk objects, and centaurs. Then we combined the orbital data to calibrate the angular momenta of these small bodies, and evaluated the specific contribution of the massive dwarf planets. The effects of uncertainties on the mass determination and the observational incompleteness were also estimated. Results. We determine the total angular momentum of the known minor planets to be 1.7817 × 1046 g cm2 s−1. The relative angle α between this vector and the total angular momentum of the Sun-planets system is calculated to be about 14.74°. By excluding the dwarf planets Eris, Pluto, and Haumea, which have peculiar angular momentum directions, the angle α drops sharply to 1.76°; a similar result applies to each individual minor planet group (e.g., trans-Neptunian objects). This suggests that, without these three most massive bodies, the plane perpendicular to the total angular momentum of the minor planets would be close to the invariable plane of the solar system. On the other hand, the inclusion of Eris, Haumea, and Makemake can produce a difference of 1254 mas in the inclination of the invariable plane, which is much larger than the difference of 9 mas induced by Ceres, Vesta, and Pallas as found previously. By taking into account the angular momentum contributions from all minor planets, including the unseen ones, the orientation improvement of the invariable plane is larger than 1000 mas in inclination with a 1σ error of ∼50−140 mas.

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.

scholarly journals Microscopic analysis of homogeneous electron gas by considering dipole–dipole interaction

2017 ◽  
Vol 31 (35) ◽  
pp. 1750334 ◽  
Author(s):  
G. H. Bordbar ◽  
F. Pouresmaeeli
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Electron Gas ◽  
Microscopic Analysis ◽  
Dipole Interaction ◽  
Angular Momenta ◽  
State Dependent ◽  
Analytic Expressions ◽  
Quantization Formalism ◽  
The Impact

Implying perturbation theory, the impact of the dipole–dipole interaction (DDI) on the thermodynamic properties of a homogeneous electron gas at zero temperature is investigated. Through the second quantization formalism, the analytic expressions for the ground state energy and the DDI energy are obtained. In this paper, the DDI energy has similarities with the previous works done by others. We show that its general behavior depends on density and the total angular momentum. Especially, it is found that the DDI energy has a highly state-dependent behavior. With the growth of density, the magnitude of DDI energy, which is found to be the summation of all energy contributions of the states with even and odd total angular momenta, grows linearly. It is also found that for the states with even and odd total angular momenta, the DDI energy contributions are corresponding to the positive and negative values, respectively. In particular, an increase of total angular momentum leads to decline in the magnitude of energy contribution. Therefore, the dipole–dipole interaction reveals distinct characteristics in comparison with central-like interactions.

scholarly journals Angular Momentum Growth around Local Density Maxima

1988 ◽  
Vol 130 ◽  
pp. 552-552
Author(s):  
A. F. Heavens ◽  
J. A. Peacock
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Power Spectrum ◽  
Total Angular Momentum ◽  
Cold Dark Matter ◽  
Local Density ◽  
Probability Distributions ◽  
Power Spectra ◽  
Elliptical Galaxies ◽  
Angular Momenta

We have calculated the growth of angular momentum about local density maxima at early epochs. We find that high peaks experience higher torques than low peaks, counteracting the short collapse time during which the high peaks can acquire angular momentum. Which effect is dominant depends on the perturbation power spectrum: for power spectra characteristic of both cold dark matter and hot dark matter, the effects nearly cancel, and the total angular momentum acquired by a collapsing object is almost independent of the height of the peak. Furthermore, the distributions of angular momenta acquired by collapsing protosystems are extremely broad, for all power spectra, far exceeding any modest differences between peaks of different height.These results indicate that it is not possible to account for the systematic differences in angular momentum properties of disk and elliptical galaxies simply by postulating that the latter arise from fluctuations of greater overdensity, contrary to some recent suggestions. The figure shows the probability distributions for the final angular momentum acquired by peaks of dimensionless height 1–4, for a power spectrum similar to cold dark matter. A fuller account of this work has been submitted to MNRAS.

scholarly journals Numerical Experiments on the Decay of Three-Body Systems

1977 ◽  
Vol 33 ◽  
pp. 163-166
Author(s):  
M. J. Valtonen ◽  
S. J. Aarseth
Keyword(s):  
Angular Momentum ◽  
Total Angular Momentum ◽  
Mass Difference ◽  
Large Mass ◽  
Equal Mass ◽  
The Other ◽  
Escape Probability ◽  
Triple Systems ◽  
Three Body ◽  
Very High

AbstractNumerical results are presented for calculations of stellar three-body systems. Among the triple systems with similar initial separations between each of the stars, the equal-mass systems are most stable with typical half-lives of about 40 crossing times. In the other extreme, systems with a very small total angular momentum or a large mass difference have half-lives of only about 10 crossing times. The escaping star is usually the lightest one, while the escape probability for the heaviest star approaches zero when its mass exceeds the combined mass of the other two stars by more than a factor of about 5. The final binary becomes very eccentric (ē ≳ 0.8) when the three stars are restricted to a plane and do not have a very high total angular momentum, or when the total angular momentum is very small.

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.

Upper Extremity Function in Running. II: Angular Momentum Considerations

1987 ◽  
Vol 3 (3) ◽  
pp. 242-263 ◽  
Author(s):  
Richard N. Hinrichs
Keyword(s):  
Angular Momentum ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Vertical Component ◽  
The Body ◽  
Lower Trunk ◽  
Body Center ◽  
Recreational Runners ◽  
Total Body ◽  
Angular Impulse

Ten male recreational runners were filmed using three-dimensional cinematography while running on a treadmill at 3.8 m/s, 4.5 m/s, and 5.4 m/s. A 14-segment mathematical model was used to examine the contributions of the arms to the total-body angular momentum about three orthogonal axes passing through the body center of mass. The results showed that while the body possessed varying amounts of angular momentum about all three coordinate axes, the arms made a meaningful contribution to only the vertical component (Hz). The arms were found to generate an alternating positive and negative Hzpattern during the running cycle. This tended to cancel out an opposite Hzpattern of the legs. The trunk was found to be an active participant in this balance of angular momentum, the upper trunk rotating back and forth with the arms and, to a lesser extent, the lower trunk with the legs. The result was a relatively small total-body Hzthroughout the running cycle. The inverse relationship between upper- and lower-body angular momentum suggests that the arms and upper trunk provide the majority of the angular impulse about the z axis needed to put the legs through their alternating strides in running.

Sign in / Sign up

Export Citation Format

Share Document