# Virtual velocity

## Definitions

• Webster's Revised Unabridged Dictionary
• Virtual velocity (Mech) a minute hypothetical displacement, assumed in analysis to facilitate the investigation of statical problems. With respect to any given force of a number of forces holding a material system in equilibrium, it is the projection, upon the direction of the force, of a line joining its point of application with a new position of that point indefinitely near to the first, to which the point is conceived to have been moved, without disturbing the equilibrium of the system, or the connections of its parts with each other. Strictly speaking, it is not a velocity but a length.
• Virtual velocity See under Virtual.
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## Usage

### In news:

And 2,710-16,305 rpm, with ultra-smooth velocity and virtually no eddy current or hysteresis losses.
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### In science:

In particular, we have placed a virtual “observer” at 8.0 kpc from the simulation centers, looking in the actual SDSS directions and sampling radial velocities for stars that are more than 4 kpc above and below the disk plane.
The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
In the regime of x → 0+ , there exists a free-fall asymptotic solutions for which the gravity is virtually the only force in action, and the radial velocity and the mass density proﬁle both diverge in the limit of x → 0+ .
Self-Similar Polytropic Champagne Flows in H II Regions
Referring to Fig. 1, let’s imagine that there is a small virtual box adhering to a moving particle, represented by ∆x∆y∆z symbolically, and imagine that we are able to count the number of the inside particles whose velocities are within a small range, represented by ∆vx∆vy∆vz symbolically.
A counterexample against the Vlasov equation
We add the Hubble ﬂow to the z -direction of the velocities of galaxies in our simulation box, and we place all galaxies at a minimum distance of 60 Mpc from the virtual observer, so that all clusters are at least as far away as the nearest cluster in the sample of vdL07.
Cluster Galaxies Die Hard
This second point is solved by making the ﬂuid virtually span outside Ωt and by setting its velocity there to zero with a penalization method (also called immersed boundary method) [25, 5].
The camera method, or how to track numerically a deformable particle moving in a fluid network
Measuring the virtual photon yield as a function of mass and momentum is the next step beyond existing data to separate temperature and ﬂow velocity and map out the space-time evolution of the system.
sPHENIX: An Upgrade Concept from the PHENIX Collaboration
This, however, does not necessarily mean that the proﬁle will be poorly determined: as shown in Section 5, virtually all uncertainty (at γ = 3.4) is due to the existence of a single linear combination of velocity dispersion parameters that is poorly constrained even by parallax microlensing.
Halo structure, masses of dark objects and parallax microlensing
Here it is instructive to note that in the case of weak dissipation, the Fermi velocity vF = n1 pF /ρ1 is negligibly small compared with the characteristic velocity p2U0/M (Rc ) of a virtual droplet moving under the potential barrier.
Effects of hyperons on the dynamical deconfinement transition in cold neutron star matter
The velocity of sound, cs ∼ 0.5c, of hyperonic matter cannot fully surpass the rate | ˙R| of growth of a virtual droplet ranging typically ∼ 0.1–1c.
Effects of hyperons on the dynamical deconfinement transition in cold neutron star matter
It may also be assumed that the energy dissipation and dynamical compressibility in hadronic matter have no inﬂuence on the pre-exponential factor, because the velocities vF,H and cs take on nearly the same order of magnitude as the rate | ˙R| of growth of a virtual droplet.
Effects of hyperons on the dynamical deconfinement transition in cold neutron star matter
In the calculations ignoring the presence of hyperons, we have found that the effective mass of a virtual droplet moving under the potential barrier is suﬃciently large to keep its growth rate fairly small compared with the Fermi velocity averaged over nucleon species.
Effects of hyperons on the dynamical deconfinement transition in cold neutron star matter
In the CM frame the energy, but not the momentum, of the virtual photon vanishes so that its velocity, v , is inﬁnite. A recent experiment measuring the distance-dependence of magnetic induction has veriﬁed experimentally this prediction [16, 17].
The physics of space and time II: A reassessment of Einstein's 1905 special relativity paper
Then we show that if we simply model the propagation of a photon in vacuum as a succession of transient captures with virtual pairs, we can derive a ﬁnite velocity of the photon with a magnitude close to the measured speed of light c.
Does the speed of light depend upon the vacuum ?
Then we show that if we simply model the propagation of the photon in vacuum as a series of interactions with virtual pairs, we can derive a velocity of the photon with a magnitude surprisingly close to the measured speed of light.
Does the speed of light depend upon the vacuum ?
This bare velocity corresponds to a velocity of light in an empty vacuum with no virtual particle.
Does the speed of light depend upon the vacuum ?
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