Physics Questions, Problems & Solutions : TransWikia.com ~ Page 157

Understanding time crystals

In very recent publications, two groups in Maryland (paper: "Observation of a Discrete Time Crystal") and Harvard (paper: "Observation of discrete time-crystalline order in a disordered dipolar many-body...

Asked on 07/26/2021 by user929304

1 answer

Boundary condition on $mathbf{B}$ to describe resonant cavities from waveguides

In Jackson- Classical Electrodynamics when resonant cavities are discussed (8.6, page 252) (but also at page 7 here or at page 19 here)...

Asked on 07/26/2021

1 answer

Ball suspended on a string

If you have a ball spinning on a string which is attached to a pole, will it keep spinning in the absence of any friction/air resistance/other retarding forces? I'm trying...

Asked on 07/26/2021

1 answer

Friction during ball backspin and overspin

I already know sliding friction of ball on a flat table and rolling resistance of it. How do I know coefficient of friction value when the ball has backspin with...

Asked on 07/26/2021 by user2229336

2 answer

Why is shear stress equal to half of yield stress?

Why is the value for acceptable shear stress equals to half of yield stress? $$ tau = frac{sigma_{yield}}{2} $$P.s Along the math behind it would be possible...

Asked on 07/26/2021 by Jek Denys

2 answer

Expectation value of commutator $langle p|[hat{x},hat{p}]|prangle$

For commutator $langle p|[hat{x},hat{p}]|prangle$, we can compute it as $$langle p|[hat{x},hat{p}]|prangle = langle p|hat{x}hat{p}|prangle-langle p|hat{p}hat{x}|prangle=plangle p|hat{x}|prangle-plangle p|hat{x}|prangle=0,$$ but also$$langle p|[hat{x},hat{p}]|prangle = langle p|ihbar|prangle=ihbar,$$ where is the...

Asked on 07/26/2021 by J.-H.

1 answer

Three blocks and the representation of $S_3$

I've been studying chapter 1 of the famous group "Lie Algebras in Particles Physics" by Georgi.I am rather confused by section 1.16.The claim is the following. Consider a...

Asked on 07/26/2021 by Einj

0 answer

Understanding Cosmological Perturbation Equations

I am writing to numerically solve the following coupled first order partial differential equations. First I am trying to rewrite them in a more favorable way. In ther equations below...

Asked on 07/26/2021

0 answer

Electric charge operator in the $SU(3)_{C} times SU(3)_{L} times U(1)_{X}$ model

The 3-3-1 extension of the Standard Model of the strong and electroweak interactions, with gauge group $SU(3)_{C} times SU(3)_{L} times U(1)_{X}$, provides an attempt to answer the question on...

Asked on 07/26/2021

1 answer

Quanta of fields

I just heard the term quanta of a field. I’m trying to understand it. Does it mean that field starts acting in a way that is measurable or singularly measurable?...

Asked on 07/26/2021 by Bluesby

1 answer

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