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1answer
9 views

How to calculate the coefficient of kinetic friction using deceleration?

The original question is: A sled is pushed along a snowy road with velocity $v = 2.5\,\mathrm{m/s}$. When it is released, it glides along for $6.4\,\mathrm m$ before coming to rest. Find the ...
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0answers
8 views

Historical meaning of action

In the Feynman lectures, it is stated Also, I should say that $S$ is not really called the ‘action’ by the most precise and pedantic people. It is called ‘Hamilton´s first principal function.’ Now ...
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1answer
22 views

Does any force on a spring make it oscillate?

If I push one end of a spring (while the other end is attached to a rigid support) with a force of F and over a distance of $x = F/k$, it is only after a the end of the spring has been displaced x ...
-4
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0answers
104 views

What temperature increase results from the current 410 PPM spike in $CO_2$?

https://skepticalscience.com/skakun-co2-temp-lag.html?fbclid=IwAR2A_wvpTcWfdMjZsY_64JELzKt592FpXX8Q1UtIopgvoq3t8TqaThBGyxc So while CO2 did lag behind a small initial temperature change (which mostly ...
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0answers
5 views

collision (elastic and inelastic)

An object A of mass 2kg is moving with a velocity of 3m/s and collides head on with an object B of mass 1kg moving in opposite direction with a velocity of 4kg . After collision they stick together. ...
3
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1answer
111 views

Quantization of Klein-Gordon field between two boundaries

Consider a real scalar $\phi(x,t)$ with mass $m$ in $1+1$ dimensional spacetime, described by the 2d free Klein-Gordon action. $\phi(x,t)$ lives on an interval $0 \leq x \leq L$, and is subject to ...
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0answers
5 views

Can liquid hydrogen be ionized?

Does stripping the electrons off of hydrogen atoms affect it's boiling point in any way?
1
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1answer
14 views

Difference between Displacement-time graph and Position-time graph

While going through my physics book, I got over a question which ask us to plot a position-time graph for the interval ($t=0\,\mathrm s$ to $t=5\,\mathrm s$) From the top of a tower, a ball is ...
0
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1answer
20 views

What is infinitesimal displacement?

This section is from the Openstax University Physics: Volume 1 online textbook. In physics, work is done on an object when energy is transferred to the object. In other words, work is done when a ...
6
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3answers
591 views
+50

How could lightning have killed 322 reindeer at one time in Norway?

Lightning is supposed to have killed 322 reindeer within an area that's about 50-80 meters in diameter on a mountain plateau in Norway. Nearly the entire herd died. Sources: (1, 2, 3, 4) Photo: ...
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1answer
30 views

In certain conditions, does a permanent magnet loses its mass over a period of time? [on hold]

While working on an alternative cosmological paradigm of, Eigen-rotational Clusters of String-matter Universe, it was hypothesized that the fundamental matter is, Eigen-rotational elastic string-...
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0answers
13 views

I want sites special of physical and chemical, contains some books of courses and exercices

I want sites and books to teach physics and chemistry, at the university how do I get that.?
0
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1answer
15 views

Higher energy of outer orbitals around nucleus

I remember reading that the outer orbitals of atom have higher energy. If an electron is given enough energy is goes to higher energy orbitals from $n=1$ to $n=2,3,4...$ My question is that why do ...
1
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3answers
207 views

What should be the direction of motion of a conductor in a magnetic field to produce motional emf?

Here's the textbook question: Twelve wires of equal length 'l' are connected to form a skeleton cube which moves with constant velocity v perpendicular to the magnetic field B. What will be the ...
0
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1answer
36 views

How can the acceleration of a person on a zipline be calculated?

I was thinking one day about how a speed, or perhaps the acceleration, of a person riding a zip line could be calculated. I first started by thinking of an ellipse where the two foci were the anchors ...
0
votes
1answer
167 views

Internal resistance and a resistor as a potential divider

Based on the fact that batteries have some kind of internal resistance, if I had a circuit that consisted of a battery and a resistor of some kind would they act like a potential (voltage) divider? ...
2
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1answer
41 views

Question regarding radial raising/lowering operator for isotropic harmonic oscillator

I understand the symmetry structure of the 3D isotropic harmonic oscillator $H = \frac{\mathbf{P}^2}{2\mu} + \frac{1}{2}m\omega^2\mathbf{X}^2$ as follows. The energy levels are $E_N = \hslash \omega (...
1
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2answers
98 views

Having some trouble with acceleration in polar coordinates

So, I solved a question about acceleration in polar coordinates, but most people in my class (Classical Physics, first year at university studying Physics) disagree with my answer. So the question is ...
3
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3answers
96 views

How does exactly time dilate in a gravitational field, and how is it judged by different inertial observers?

When I tried to answer the SE question, Clock on a pendulum, I faced an ambiguity regarding time dilation in the gravitational field. To make the argument clearer, I designed the simpler thought ...
0
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2answers
822 views

Average kinetic energy of escaping molecule from a container

I run into a question which haunts me for a while. Can anyone help me out? The problem is: Consider the effusion of molecules through an opening of diameter d in the walls of a container with ...
0
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1answer
24 views

What is a medium?

I was reading this and in there it states that The weakness of the wave theory was that light waves, like sound waves, would need a medium for transmission. The existence of the hypothetical ...
0
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0answers
11 views

Why do we need conformal compactification to define the global conformal group?

First I have the definition of a conformal map. Let $(M,g)$ and $(M',g')$ be two pseudo-Riemannian manifolds of same dimension. Let $U\subset M$ and $V\subset M'$, we say that a smooth map of maximal ...
0
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0answers
13 views

How can I plot a vector in a different system than the Cartesian system?

How can I plot a vector in a different system than the Cartesian system? Suppose I have a vector i cylindrical coordinates: $$a_{\phi} (\phi) = \cos(\phi)\tag{1}$$ On the other hand, I have a ...
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0answers
7 views

why g-force increase with radius and centrifugal force decreases?

Trying to understand the 2 formulas and the relations between radius. Common sence will tell me that centrifugal force increases while we are on a curve with a short angle , as newtons law formula ...
0
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0answers
6 views

What operating range is the ponderomotive approximation valid?

Recalling the equation on the ponderomotive force experienced by a particle in a non-uniform oscillating electric field: 𝐹=𝑞^2/4𝑚𝜔^2 grad(𝐸2), Could anyone shed light on what frequency range 𝜔 ...
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0answers
22 views

Is there a limit of electrons a single Hydrogen atom can have

If so what is it?, why? is the the answer to why scalable to Helium?
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0answers
15 views

Necesary time to let a particle at equilibrium point

I remmember that exists a demostration of this time is actually infinite, but I cannot find it. We have a potential V(x) that it had a local max, and a local min at least. If we give to a particle ...
1
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0answers
11 views

what's the physical meaning of the standard base vectors?

I can find 3 displacement $\vec d_1 ,\vec d_2, \vec d_3$ and use them as basis so that a displacement is $\vec d=a\vec d_1 +b\vec d_2+c \vec d_3$. I can find 3 forces $\vec F_1 ,\vec F_2, \vec F_3$ ...
2
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4answers
89 views

How do “many worlds” theorists explain particle double-slit interference patterns?

In the past couple of weeks I’ve re-watched Sidney Coleman’s wonderful 1994 lecture “Quantum Mechanics” in Your Face” and Sean Carroll’s 2019 Google talk “Something Deeply Hidden: Quantum Worlds & ...
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1answer
109 views

Making sense of the Buoyancy force [duplicate]

I was reading about how to find the buoyancy force when I came across this explanation: Imagine a box submerged in a tank of liquid. The distance from the surface of the liquid to the bottom ...
0
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0answers
11 views

Does the same object have less mass on Earth than in space?

Would it be true to say a person is less massive on the surface of the Earth than they are in space because they have less potential energy? Would the Earth also be reduced in mass slightly?
0
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0answers
16 views

Mass spring system [on hold]

I have a question that i cant figure it out. I would be so pleasent if you can help me.
1
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1answer
15 views

cold fusion with ionized hydrogen and neutron radiation

Would bombarding ionized hydrogen gas with neutron radiation cause cold fusion as the neutrons have no electrostatic repulsion to overcome therefore making it much easier to get within range of the ...
2
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0answers
36 views

Oil droplet in Electric field [on hold]

suppose a horizontal plate capacitor. They are separated by $d=0.005 \text{m}$. In a homogeneous field, the oil droplet ($m=3\cdot 10^{-15} \text{ kg}$) sits at the bottom of the lower plate. Like a ...
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4answers
45 views

Quantum mechanics Interference

While learning wave-particle duality of an electron I found the wave with which we associate the electron is the probability wave. Now my questions are that if that is so How do electron show ...
1
vote
1answer
116 views

Contradictory solutions to the Klein-Gordon equation as an initial value problem (canonical formulation)

I'm going to begin with a prelude about constructing the solution using the action/Lagrangian formalism in order to provide context and a point of comparison for the canonical one. The main question ...
0
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1answer
4 views

Effects of positions of object in lens problemd

there was a question in which the object is place right side of a concave lens so I decided as usual like taking objects position as positive and considering the right face of the concave mirror so I ...
0
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1answer
22 views

Calculating RPM of a motor

I am trying to calculate the optimal RPM of a DC motor in order to move a car. I know that the force exerted on the wheel by the motor is: $$ F=9N $$ I also know the following information ("h" ...
2
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0answers
18 views

Would an infinitely (or very long) diffraction grating produce a diffraction pattern?

Take a typical science lab diffraction grating which is producing a pattern on a screen. Let's consider the location of say the first maximum on the right side. Let's draw straight lines from the ...
1
vote
0answers
30 views

The rate of change of a relativistic electron energy

I am trying to derive the equation for the rate of change of the energy for a relativistic electron. I know I should start from the following equation: $$\frac{d(\gamma m\vec{v})}{dt}=-e(\vec{E}+\vec{...
0
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0answers
15 views

Electromagnetism

Consider two balls (starting at zero speed) rolling down under the force of gravity inside conducting copper (non- magnetic material) tubes; the red ball is magnet and blue is not. a. Are current ...
0
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0answers
10 views

How does a twisted piece of string/yarn wind back on itself? What kinds of forces are responsible for this?

I do a lot of fibrework (carding wool, spinning yarn, weaving, etc.) and I've noticed a funny behaviour that anything long and flexible, which can withstand significant torque exhibits. If I take a ...
0
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2answers
35 views

System kinetic energy interpretation(edited)

How can I make a “further interpretation” of the 2nd term of system kinetic energy when it comes to “fluids”? (Possibly deformable body, too) Linked pdf below is not lecture note of mine, however, my ...
2
votes
1answer
31 views

What do you see in 'A Boy and His Atom'

A boy and his atom is a short movie by IBM animated by actually moving atoms around and using a scanning tunneling microscope to display the result. When I first saw this picture I was fascinated ...
0
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0answers
25 views

How much $^{56}Ni$ is needed to power a supernova of $10^{44}J$ energy? [on hold]

Folks, Apologies for this question, A supernova has a KE of 10^30 J and it is powered entirely from 56Ni decay. How much 56Ni is needed? I was looking for pointers in what formula is us or how to ...
0
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0answers
7 views

What does 'Impinging a fluid to rest mean'?

I am learning fluid dynamics for my math graduation , and as such don't have a physics background for this subject . I came across the following question following question : Part 1 : A sphere of ...
2
votes
1answer
125 views

Can one force the octupole moments of a charge distribution (neutral and with vanishing dipole moment) to vanish using a suitable translation?

In a previous question, I noted that if you have a charge distribution with nonzero charge, then it is possible to choose an origin (at the centre of charge) which makes its dipole moment vanish, and ...
11
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4answers
535 views

Justification for excluding gravitational energy from the stress-energy tensor

I did general relativity years ago at Uni and was just revising with the aid of Dirac''s brilliant book; the beauty of this book is that it is so thin and concise. On reading this book I find that I ...
0
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1answer
24 views

Energy release from beta decay

It is difficult for me to understand how beta decay releases energy. The neutron is more massive than a proton, electron and antineutrino combined. Would this not imply that energy is being ...
2
votes
3answers
407 views

Schrödinger's equation - Time reversal

While reading a book about interactions I've come to this paragraph: In the Schrodinger representation, the state function satisfies the equation $$\mathrm{i}\frac{\partial}{\partial t}\phi(t,x)=H\...

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