All Questions

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2 views

Biophysics Concentrations homework question, Question (a) and (b)

Homework Problem for biophysics course I honestly am not sure how to proceed to determine the concentrations, the only hint professor gave me was to use equilibrium K and the fact it was neutral to ...
0
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0answers
4 views

From XFlow CFD to Hololens/AR

I have to export a mesh plus computational data from XFlow and put it on a HoloLens device to show how a meshed object with a steam flow on it appears in an augmented reality environment. Can you help ...
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0answers
10 views

Strain Rate Tensor and Rotation Tensor

How can I prove that $S_{ij}$ (strain rate tensor) is zero for the flow field $u = U + \Omega \times x$ , where $U$ and $\Omega $ are constant linear- and angular velocity vectors by using Cartesian ...
-2
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0answers
12 views

Could Dark Energy actually be gravity from unimaginable mass outside our universe?

If there is a huge amount of mass outside of our observable universe, could that explain the universe expansion?
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0answers
12 views

Yet another kinematics question with non-uniform gravitational acceleration [on hold]

A problem is posed where an object is launched into the atmosphere from the surface of the earth at such an initial velocity that it comes back to the surface of the earth after a specific time t. ...
1
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2answers
16 views

Why is the laboratory frame energy always greater than the center of mass frame energy?

I have been looking for an answer to 'Why is the laboratory frame energy always greater than the center of mass frame energy during collisions?'. A lot of resources provided mathematical explanations....
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0answers
15 views

Do charges in a metal group up a little in the middle?

Around the edges of a metal, the density of electrons is higher than the rest of the metal. I think this is because every electron is surrounded by neighbours pushing them away but once you get to the ...
-5
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0answers
14 views

Motion and velocity

A body at rest is given an initial acceleration of 8.0ms for 30 secs after which the acceleration is increased 12.0ms for the next 20 secs the body maintained the speed attained after which it is ...
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0answers
7 views

How does an initial velocity affect the tangential velocity when a rocket cross the poles?

I'm trying to improve a piece of code I've written to allow for shooting rockets across the poles while being affected by the coriolis force. The code is written using RK4 since we are also looking at ...
2
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0answers
19 views

I need to find the drag coefficient of a pendulum bob

Is it possible to find the drag coefficient of a pendulum bob from the damping caused on it during swinging. I will be able to measure its displacement from the point of origin and plot it against ...
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0answers
10 views

Calculating the peak-to-peak range of sinusoidal variation in noisy data; phase-sensitive detection

I have a problem in a set of questions on elimination of noise and phase sensitive detection for which I have an attempted method but the answer does not match the suggested numerical answers, and I ...
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0answers
13 views

Temporal Phase, Spectral Phase, Total Phase…

I am a little confused about the phase in the electric field as a solution to the wave equation. Phase $\phi$ The solution to the wave equation we get from Maxwell's Equations is the real-valued ...
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0answers
18 views

Mean field 3d Ising model in Landau theory

I am solving a problem for some course I am following. I am given the Hamiltonian: $$H = 3NJ \langle \sigma\rangle ^2 -6J\langle \sigma\rangle \sum_i\sigma_i,$$ where $i$ sums over all sites ($=N$)....
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0answers
14 views

How to derive the hamiltonian of general relativity (ADM formalism without surface terms)?

given that $ds^{2} =−N^{2}dt^{2} +h_{ij}(dx^{i} +N^{i}dt)(dx^{j}+N^{j}dt)$ $S=\int dt d^{3} x\sqrt{h} N(^{3}R+K_{ij}+K^{ij}-K^{2})$ where $(^{3})R$ is the Ricci scalar of hij, h the determinant of ...
-5
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0answers
31 views

Could the theory of everything be an algorithm?

I've been thinking about the theory of everything. Could the theory of everything to explain how the universe work be a computer algorithm? Is there any way to test whether the universe is a ...
-2
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0answers
14 views

Questions on velocity that are multistep? [on hold]

I know these may seem simple but I'd really appreciate how to proceed with these questions. A plane takes off from JFK heading towards Miami, which are 1765km apart. The entire trip takes 5 hours. ...
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0answers
15 views

Mode in quantum mechanic

Let suppose we have $N$ identical composite particles at ground level. Each composite particle have two distinguishable particles. Thus the state of composite bosons in ground state can be written as ...
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0answers
19 views

What is the wave nature of electron? [duplicate]

Is electron a standing wave or a probabilistic wave? or is it both? can someone explain me also what wavelength we calculate from de Broglie's equation? also does electron spin around itself? or is ...
-10
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0answers
27 views

Have we really reached moon? [on hold]

it seems like NASA and other space agencies are making fool of the whole world. i think that they are showing us just fake photos of them going there. ???? i don't know much about stack exchange , so ...
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0answers
20 views

Max Planck and energy quantization idea

Did Planck have an intuition behind the idea of energy quantization of atomic oscillators and radiation, or it was just a mathematical trick to drive his distribution law?
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0answers
7 views

Gyroscope precession direction of torque

On the opposite side of the rotation vector direction [L], when i applying force upside of rotor surface(dotted line) Why the generated torque cause the rotor to rotate counterclockwise? when i apply ...
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0answers
23 views

Attributes of the arrow of time

What are the elementary attributes of the arrow of time? The connection of entropy as a causality of the arrow of time has been logically excluded (reference available on request). Are there other ...
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0answers
13 views

Relation between height and range

The height of water level in a tank is H. The range of water stream through a hole at depth H/4 from upper water level will be.
1
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1answer
18 views

What is the physical meaning of static and velocity pressure?

According to Bernouli's equation, the static pressure inside a pipe with streamline and steady flow decreases with fluid's velocity. One explanation to rationalise this phenomenon is because velocity ...
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1answer
28 views

Why use $\ln$ in definition of pseudorapidity?

Why is pseudorapidity defined as $\eta = -\ln[\tan(\frac{\theta}{2})]$ as opposed to just $\eta = \tan(\frac{\theta}{2})$?
3
votes
3answers
52 views

According to general relativity, why are two objects at rest attracted to each other? [duplicate]

I'm trying to understand gravity in General Relativity and I'm having some questions. I can understand that an object in orbit around another more massive object is free falling and simply following a ...
1
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1answer
19 views

Double Slit vs Diffraction Grating Intensity Graph

I had a few questions regarding the intensity graphs of fringe patterns observed when light is shone through a double slit vs a diffraction grating. For a double slit, does the intensity of the ...
1
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2answers
12 views

Interesting “paradox” from class: Impulse on a rod in a vacuum results in different energy in dependence on point of impulse

This question has been somewhat addressed here, but the discussion ended a little too soon in my opinion. (Sadly, I cannot simply comment in the thread due to low reputation). Say we have a rigid rod ...
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0answers
15 views

Can the electromagnetic radiation pressure $p=u/3$ be the thermodynamic one $p(T)=u(T)/3$?

Can the electromagnetic radiation pressure $p=u/3$ be the thermodynamic one $p(T)=u(T)/3$? In electromagnetism, the radiation pressure formula $p=u/3$ does nothing with temperature at all. One quick ...
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0answers
19 views

How can a vortex be created?

i have seen this video. https://www.youtube.com/watch?v=pnbJEg9r1o8&t=96s It is not completly clear how a difference of velocity can cause a vortex, can you explain me?
2
votes
1answer
33 views

Exact equation of exponential curves of underdamped harmonic motion

I was studying the underdamped harmonic motion and got curious about the fact that the decreasing exponentials $\pm Ae^{-\gamma t}$ are good approximations only for light damping $(\gamma<<\...
0
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0answers
26 views

Standing waves on a guitar

If we play different strings we get different frequencies as the densities of the strings are different. This is described by: $$kL=n\pi$$ where $n$ is an integer, $k$ the wavenumber and $L$ the ...
0
votes
1answer
17 views

Energy of an object

When an object goes up we say that it gained potential energy but it is doing positive work on the earth so it should lose energy.Please tell correct me.
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2answers
40 views

Why are tail rotors in helicopters vertical?

I guess spinning in perpendicular direction to main rotor is better in counteracting the torque but what's the mechanism at work?
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0answers
17 views

Bremsstrahlung radiation spectra expected and total radiation emitted

As homework, I have to do the following exercise: Bremsstrahlung emission: We are interested in ionized plasma of density $n$, at temperature $T$ with ions of charge number $Z$. Explain ...
2
votes
1answer
32 views

How does the 2nd Law of Thermodynamics demand the existence of at least two thermal reservoirs in a cycle?

In my studies, I've come across Kelvin's statement of the 2nd law: It is impossible to undergo a cyclic process whose only effect is removing heat from a reservoir and generating an equivalent ...
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0answers
17 views

decay rate in two level system

From Fermi's golden rule, one knows that transition rate can be given as the following: $\Gamma_{i->f} = \frac{2\pi}{\hbar}|<f|H'|i>|^2 \rho$ However, can we make the assumption below? ...
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vote
1answer
39 views

If live & neutral alternates, why is neutral always $0V$?

So I've been confused on why the neutral is always at $0V$, I know that because it is earthed, but the concept that I know about AC Current that the Voltage keeps alternating ex(from $+240$ to $-240$)....
-3
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0answers
32 views

What's the magnitude of the resultant force? Vectors and scalars [on hold]

What is the formula required to calculate the magnitude of the resultant force. Here is an example question: Two forces, each of $10\text{ N}$, act at a point $P$ as shown in the diagram. The ...
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0answers
9 views

What are the conditions for molecular,photon resonance other than same frequency?

I know that the basic condition for molecular,photon resonance is same frequency but what are the other condition for this process like phase relationship,round trip of the molecules and so.Also can ...
2
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1answer
28 views

what kind of information is shared between entangled particles

when two entangled particles are separate by distance . what exactly happens to them , that influence us to consider they connected each other?
4
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2answers
636 views

Conservation of angular momentum on Earth

If I start spinning while standing on the floor, conservation of angular momentum says something needs to start spinning in the opposite direction but what's that?
-1
votes
2answers
58 views

Charging a battery

So we have a charger outputting V volts and $I$ Amperes and two rechargable batteries of the same capacity $Q$ coulombs but different emf's $V_1\&V_2$. Which battery would charge faster? ...
-1
votes
0answers
5 views

Clarification on Soloman A-Level (M1) moments question

In this M1 Soloman paper in Q3(b), we are asked to find in the form $k\sqrt{2}$ the value of force $X$ given that the resultant moment of all forces about $D$ is zero in the following square of width/ ...
5
votes
3answers
40 views

Why does increasing the volume in which a gas can move increase its entropy?

Let's say we have a box with a non-permeable wall separating the box in half. There is gas on the other side of the wall. Now we remove the wall so that the gas can diffuse to the other half of the ...
1
vote
1answer
67 views

Why naturalness is an issue in particle physics? It is not in fluid dynamics

I have often heard that naturalness is a strong argument in favor of Supersymmetry. They say that there must be energy scales not too far away the EW-energy so that the quantum corrections of the ...
0
votes
1answer
36 views

An accelerating rod in special relativity

If A solid rod is at rest on the x’-axis of an inertial frame $S’$. Then, at $t'_ 0 = 0$ the rod starts moving with constant acceleration a parallel to the $y’$-axis, while the frame $S’$starts moving ...
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0answers
14 views

Equations of motion for a Weyl spinor in the context of SUSY

I'm learning supergravity from the textbook of Antoine Van Proeyen (this is from page 114). Suppose I'm given a Lagrangian $$ \mathcal{L} = - \partial^{\mu} \bar{Z} \partial_{\mu} Z - \bar{\chi} \...
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0answers
17 views

To find the linear acceleration,angular velocity and friction acting on a object which can roll [on hold]

Consider a Sphere,cylinder or any other object which can role.It is on a surface of coefficient of friction μ.A force of magnitude F is applied at an angle θ to the horizontal at the bottom of the ...
1
vote
1answer
39 views

Will having two water pans in my smoker make any difference?

I have a backyard smoker, and I use a tray of water in it as thermal mass to help keep the temperature stable. I don't think the size of the tray is going to matter, but it's roughly 40cm x 30cm x ...

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