0
votes
0answers
22 views
Newton's Second Law Equivalent in rotational dynamics
The law that
$$\frac{d\vec{L}}{dt}= \vec{T}$$
where $\vec{T}$ is torque about a frame's origin $o$ and $\vec{L}$ is the angular momentum about that origin $o$.
Can this law be ultimately (always?) ...
1
vote
0answers
17 views
product of vev's vs. vev of product
How can we prove that $$\langle \phi_1 \phi_2 \rangle = \langle \phi_1 \rangle \langle \phi_2 \rangle,$$
where brackets denote expectation value on some vacuum state, and $\phi_i$ are constant fields ...
0
votes
3answers
41 views
Why does a rod rotate?
I'm a physics tutor tutoring High School students. A question confused me a lot.
Question is:
Suppose a mass less rod length $l$ has a particle of mass $m$ attached at its end and the rod is ...
0
votes
0answers
34 views
Geometry for Physics [duplicate]
I am currently a high school student interested in a research career in physics. I have self taught myself single variable calculus and elementary physics upto the level of IPHO . And I am comfortable ...
0
votes
0answers
23 views
Problem in geometrical optics [duplicate]
I was trying to solve a problem taken from an Physics Olympiad when I came across a curious and complex mathematical expression. I can not prove with what I know so far about mathematics, does could ...
0
votes
1answer
35 views
Symmetry breaking with Lagrangian
I have been studying the spontaneous symmetry braking from Zee (Quantum Field theory ) and found in the page 224, he wrote the lagrangian as
$$\mathcal{L}=
\frac{1}{2}\{
λ
(∂φ)^2 + μ^2φ^ 2\} − ...
2
votes
3answers
41 views
Why are alpha particles such a prominent form of radiation and not other types of nucleon arrangement?
It is said in many text books that alpha decay involved emitting alpha particles which are very stable. Indeed, the binding energy (~28.3MeV*) is higher than for Z-neighboring stable isotopes. But the ...
0
votes
1answer
23 views
Magnetic induction in solenoid
I found an equation in theory about magnetic induction in a solenoid: $B_s=\mu_0 I n$. It should be magnetic induction for infinite length solenoid. I wonder if this is anyhow useful. Where can this ...
1
vote
1answer
37 views
Does tapping at the side of a bottle prevent shaken soda from bubbling over?
Anecdotal evidence has it that a bottle of soda that was heavily shaken will not bubble over if tapped at the side multiple times.
Yet I wonder: Has the tapping really any effect? Or could it be that ...
1
vote
0answers
20 views
Retarded time Lienard Wiechert potential
In a potential which needs to be evaluated at the retarded time, is this the time which represents the actual time the "physics" occurred? So $t_{\text{ret}}=t-\frac{r}{c}$, not just because it may be ...
0
votes
1answer
16 views
Nodes and Antinodes for standing wave
In the arrangement shown in the figure below, an object of mass m can
be hung from a string (linear mass density $\mu$ = 2.00 g/m) that passes over
a light (massless) pulley. The string is connected ...
0
votes
0answers
32 views
Conservation of angular momentum tensor $L^{\mu\nu}$ in special relativity [duplicate]
Is relativistic angular momentum tensor $L^{\mu\nu}$ conserved the same way that the 3-vector is? Why is it a tensor and not just a 4 vector? I understand that it comes from:
$$L^{\mu\nu}~=~x^\mu ...
-1
votes
0answers
33 views
Very Hard Human Verification CAPTCHA!. (meta) [closed]
Why displayed human verification CAPTCHA is too hard!?.
it waste my time.
"words are a little too much unusual"
-1
votes
1answer
46 views
What is mathematical definition of a strong gravity?
Mathematical definition of a weak gravity is simple $g=\frac{GM}{r^2}$
but what is mathematical definition of a strong gravity? (blackhole-like or close to a blackhole-like object)
0
votes
2answers
35 views
Bremsstrahlung: why is electron slowed/stopped by the positive nucleus?
I can't understand why the electron is slowed/stopped by the nucleus.
The electron is a negative charge and the nucleus is positive... they should attract each other...
