0
votes
0answers
5 views

Liquid metallurgy [on hold]

I want to know more about liquid metallurgy? all i know it is a technique used for fabrication of material. Please help me if you know about this technique. Thank you.
0
votes
1answer
38 views

How is a irreversible process (conventionally) represented on a $T-S$ plane and why cannot it be (really) represented?

A reversible process can be represented on a $T-S$ plane, and the area under the curve is the heat exchanged by the system. On $P-V$ plane a irreversible process is conventionally represented with a ...
2
votes
1answer
45 views

Clarifications on Ampere's Law [on hold]

I have just learnt Ampere's Law, useful for calculating the magnetic field in situations having a high degree of symmetry. However, I have some conceptual doubts regarding it: Before I begin, I would ...
0
votes
0answers
22 views

Is mass relative? [duplicate]

This question has to do with the relativistic mass of an object. I have been reading that as energy increases, so does mass to a much lesser extent, and that this applies to kinetic energy as well. ...
1
vote
1answer
39 views

Vacuum persistance amplitude

E. Fradkin's Field Theories in Condensed Matter Physics formulas 3.57 and 3.58: I feel really sad about it, but all my tries of getting from formula $$ Z = \operatorname{tr} \hat{T} \prod_{j=1}^{...
0
votes
0answers
9 views

Charpy problem, Impact velocity [on hold]

Calculate the velocity of the hammer of an impact testing device at its lowest position if the hammer starts moving at an angle 30° to the horizontal (mass of rod=0.5kg, length of rod 400mm. mass of ...
4
votes
2answers
748 views

What causes Potassium to decay into Argon the way it does

From evolutionwiki: "Potassium 40 decays into argon 40 through a process known as electron capture. In electron capture, an electron from the innermost electron shell "falls" into the nucleus, ...
0
votes
0answers
10 views

I can't get the right solution to this thermal expansion problem [on hold]

The problem : A glass flask is filled to 'the mark' with 60 cm3 of mercury at 20 ºC. If the flask and its contents are heated to 40 C ºhow much mercury will be above the mark? $\alpha$ for glass : 9....
0
votes
2answers
59 views

Why is the magnetic force not (never) in the opposite direction

In this question I'm talking about the left-handed orientation for the direction of the $x$, $y$ and $z$-axis. This is the coordinate system at the left of the picture below. I learnt that when you ...
0
votes
0answers
22 views

Conditions to find standing waves harmonics

I came up with a doubt on standing waves conditions. The type of question I find difficult to answer is of the following type. Consider a rope. I do not know if the rope is fixed at both end or at ...
0
votes
0answers
17 views

Physics problem: stage of rocket [on hold]

A manned rocket is rising with a velocity of 3 km/s. At exactly 2000m, it disconnects the first rocket stage. How long does it take the stage to hit the ground, and what is the velocity of impact.(...
2
votes
3answers
75 views

Thermal energy of a system

If I had a hot cup of tea and I added to it cold milk, what would happen is that tea will lose some of its thermal energy to the milk. But why do we notice that our liquid is no longer as hot as ...
-4
votes
0answers
34 views

how to work out the probability of walking through a wall [on hold]

I was in science on Friday and I asked my teacher how to calculate the probability of walking through a wall.I just was curious because I like learning quantum mechanics
-1
votes
0answers
19 views

What is the physical meaning of source function in Radiative transfer? [on hold]

What is the importance of source function?What does that actually mean? I know that it's a ratio of emission coefficient to absorption coefficient. But I am not able to understand its physical meaning....
0
votes
0answers
12 views

Calculate velocity $v$ [on hold]

A lorry of mass $3.5\times10^4\text{ kg}$ attains a steady speed $v$ while climbing an incline of $1$ in $10$ with its engine operating at $175$ kW. Find $v$. $g=10ms^{-2}$. Neglect friction. The ...
1
vote
3answers
49 views

Can sound travel in the form of transverse waves?

We all know that sound is a longitudinal wave but in some books, I have found that sound travels in the form of both longitudinal and transverse waves while passing through rocks. Can anybody explain ...
4
votes
3answers
226 views

Are there Gauge fields that are not 4-vectors?

In my understanding Gauge fields are fields that have some kind of redundancy, i.e. a transformation that does not change the physical state. As far as I can see all the Gauge fields in the Standard ...
-4
votes
2answers
45 views

How to resolve “bottleneck” of encoding input of quantum computer? [on hold]

As far as I understand, all quantum computing purpose is to accelerate exponentially (upon input length) computation time of given task. But here user faces bottleneck to serialize input, and ...
1
vote
1answer
49 views

Can we derive Biot Savart law from Coulomb's law?

Can we derive Biot Savart law from Coulomb's law by setting a current source at an instant in place of one of the charges? Let's say $dl$ is the length of the conductor having $dQ$ charge which ...
0
votes
1answer
26 views

Energy loss of photons crossing a dielectric medium

How much energy do photons lose when crossing an "isotropic" dielectric medium? What would be possible mechanisms. I assume the straight forward answer would be that the photon loses zero energy and ...
0
votes
0answers
31 views

What is the irreducible decomposition of the tensor product of left and right weyl spinor representations, i.e. $(1/2,0)⊗(0,1/2)$?

What is the irreducible decomposition of the tensor product of left and right weyl spinor representations of the group $SL(2,\mathbb{C})$, i.e. $(1/2,0)⊗(0,1/2)$? I mean, the tensor product of two ...
0
votes
1answer
26 views

Why does a blue book appear black in red monochromatic light?

Why does a blue book appear black in red monochromatic light? I found the question on this website but it doesn't provide an explanation.
0
votes
0answers
27 views

How to measure the spin of a particle?

How we can measure the spin of a particle from the angular distribution of its decay products? for spin zero particle the distribution is flat while for spin 1 particle the distribution is different, ...
0
votes
0answers
5 views

Acceleration as a function of time in Newtonian gravity [duplicate]

In Newtonian gravity, you have acceleration as a function of separation distance $r$ as $a(r) = GM/r^2$. I need to derive acceleration as function of time, i.e. $a(t)$. PS I got into this when I ...
2
votes
1answer
58 views

Is the age of the Universe relative to where you are within it? [duplicate]

The accepted age of the Universe is 13 billion years give or take. If you were a super space being and hypothetically had spent a large portion of this time sitting next to a black hole then your ...
1
vote
0answers
26 views

Is measuring the speed of light using energy and wavelength cyclical?

I would like to measure the speed of light by directly measuring the frequency and wavelength of a light source. In order to determine the wavelength, I wanted to use a diffraction grating and the ...
-1
votes
0answers
32 views

How to find the Average Speed in this question? [on hold]

If the average speed of a spaceship is 32,000 km/h, how long would it take to travel the 80 million km from Earth to Mars? I applied the S = D / T Formula and got 0.0004 h Because this is a ...
0
votes
0answers
14 views

Evaluating an integral [migrated]

I have problem to evaluate the following integral: $$I=\int_{0}^{2\pi} \frac{\sin^2\phi\, d\phi}{a+b \cos{\phi}}$$ In fact I calculate it using complex integration methods, by changing the variable : $...
4
votes
2answers
113 views

What is the black hole information paradox really? [on hold]

Preliminaries What is the black hole information paradox really? Is it a sophisticated way to ponder and debate the existence of an operator on the boundary that can tease out the interior of a ...
0
votes
1answer
27 views

Newtonian mechanics, block on conveyor belt [on hold]

The coefficient of friction $\mu$ between the block and the conveyor belt is $0.3$ and the belt is moving with a speed of $6m/s$ when a block is dropped onto it from rest. Find the time when the ...
0
votes
2answers
48 views

Relation between entropy and internal energy

I am confused as to what is the relation between entropy and internal energy. Entropy is always presented as a measure of the randomness in a system. So when we supply heat to a well insulated system ...
0
votes
0answers
5 views

How do i calculate leakage current in passivation layer of GaN HEMT?

I want to calculate the leakage current between the passivation and encapsulation layers of the GaN HEMT which will give me information about the material
0
votes
1answer
43 views

How can I send a message to myself in the past? [duplicate]

It is easy to send a message to myself in the future: I can put a letter in the post and will receive it tomorrow. Can you think about a way to send a message to myself in the past; it does not need ...
2
votes
0answers
21 views

Change of energy of a shortening simple pendulum (Ehrenfest Pendulum) [on hold]

I've been going through Lanczos' Variational Principles of Mechanics and have been struggling with a problem that seemed pretty straightforward: A simple pendulum hangs from a fixed pulley. The ...
0
votes
1answer
28 views

What is the fate of a hyper-sphere universe?

This PBS video postulates a positively curved universe which is in the shape of something the narrator calls a "hypersphere". http://youtu.be/AwwIFcdUFrE?t=6m33s Such a universe would have no edge, ...
1
vote
3answers
78 views

Length contraction in special relativity: can space be at rest in any frame?

Suppose a rod is moving at speed $v$ relative to me along its length. $L_0 = {}$length of the rod in the frame in which the rod is at rest $L = {}$length of the rod in my frame Then $$L = L_0 \sqrt{1-...
-1
votes
1answer
31 views

Melting aluminium foil in a microwave [on hold]

Is it possible to melt aluminium foil in a microwave? I have made a lot of shapes using aluminium foil, and i wish to melt then slightly Simple, is it possible in a simple microwave oven
0
votes
2answers
54 views

Why haven't we created a material that is completely invisible to the human eye? [on hold]

From what I understand, If something was not reflecting photons in any direction, you could then see through it. If photons transfer into thermal energy could something very cold help? Could the ...
1
vote
1answer
30 views

Orientation from acceleration?

I have an object that has a sensor attached on it. This sensor calculates the acceleration in all axis and angular acceleration in all axis(Keep the gravity force in mind). How can I get the Pitch, ...
-2
votes
1answer
43 views

What can shield a Ultrasonic Weapon? [on hold]

What can shield against a ULTRASONIC weapon? https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Sonic_weapon&ved=...
1
vote
0answers
34 views

Firing Single Photon [on hold]

We know (or pretend to know) what will happen if we fire one photon at a time and let it pass through slit/slits. But what if we don't use slit/slits and fire photons one at a time at a screen? What ...
0
votes
1answer
28 views

Weak decay iff or if strangeness changes? [duplicate]

I know that for a decay if the strangeness changes then the decay is a weak decay because strangeness is conserved in both strong decays and electromagnetic decays. However, is it also true that if a ...
0
votes
1answer
27 views

Electric Field of Bar [on hold]

Problem: Positive charge $+Q$ is distributed uniformly along the positive $x$ axis from $x = 0$ to $x = a$. Negative charge $-Q$ is distributed along the $-x$ axis from $x = 0$ to $x = -a$. A point ...
0
votes
1answer
20 views

Defining Uniform Motion

According to Wikipedia the definition of motion is: In physics, motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance, ...
0
votes
1answer
18 views

The directions of the frictional force acting on the cylinder while ascending and descending cylinder

A cylinder rolls up an inclined plane,reaches some height,and then rolls down without slipping throughout these motions.The directions of the frictional force acting on the cylinder (A)While ...

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