What is Shell: Definition and 783 Discussions

CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residing in IBMBIO.COM or IO.SYS) during boot. CONFIG.SYS was introduced with DOS 2.0.

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  1. ergospherical

    I Linearised gravity approach to Lense Thirring metric

    Doing some revision and getting confused. It's under GR but may as well be under electromagnetism or calculus because that is where the problem is. Taking a shell of mass ##\rho = M\delta(r-R)/(4\pi R^2)## and four velocity corresponding to rotation about ##z## axis i.e. ##U = (1, -\omega y...
  2. shivajikobardan

    Small confusion about redirection in Linux

    https://linux-training.be/funhtml/ch18.html echo hello > greetings.txt I feel it's telling before counting the number of arguments, redirection operator is ignored. But later it says how it affects output erasing file case. [paul@RHELv4u3 ~]$ cat winter.txt It is cold today! [paul@RHELv4u3...
  3. Destroyer500

    Ramjet artillery shell of a big size

    I will copy paste a post i made on another forum.Its just a fun project i started and i hope people in here are going to be able to help.I am not an aerospace engineer but im studying electrical and electronic engineering so i am familiar with formulas math and physics (up to a degree of...
  4. Z

    MIT OCW, 8.02, Electromagnetism: Charged Cylindrical Shell

    Here is figure 2.16.6 Here is the picture I drew to set up the problem My first question is if the reasoning and integrals are correct. I used Maple to compute the three integrals. The first two result in 0, which makes sense by symmetry. Maple can't seem to solve the last integral.
  5. amyy

    A Does 15F Qualify as an sd Shell Nucleus?

    If we call a nucleus a sd shell nucleus, should its last proton and last neutron both lie in the sd shell or just one lies in the sd shell? For example, 15F, whose proton number is 9 and neutron number is 6. Then the last proton lies in the 1d5/2 orbit and the last neutron lies in the 1p3/2...
  6. alukhm

    Wood/Glass/Metal Magnet Inside a Shell containing Ferromagnetic Metal

    Hello all! I have a earring project with magnets involved but no magnet expert involved :( Here are a few stupid questions I hope someone can help us with! BACKGROUND: We are designing magnetic earrings. The earrings are meant to clamp the ear with 3 different levels of pressure. The magnetic...
  7. B

    I Observing a Collapsing Shell: Time Dilation Explained

    What does and observer inside of a collapsing shell observe? Lets say we have a shell of matter collapsing to a black hole. What would observers near the center see? How would the rest of the universe appear when, The shell is approaching the Schwarzschild radius? After the shell passes the...
  8. Povel

    A Exploring the Electric Field of a Moving Charged Spherical Shell

    The electric field inside a charged spherical shell moving inertially is, per Gauss's law, zero. If the spherical shell is accelerated, the field inside is not zero anymore, but it gains a non-null component along the direction of the acceleration, as mentioned, for example, in this paper. The...
  9. Marioweee

    Nuclear shell model of double magic nucleus 132Sn

    The independent particle energies for protons and neutrons around the exotic doubly magic core 132Sn are shown in the figure below, where π refers to protons and ν to neutrons. Using the nuclear shell model and using this figure as a guide, answer to the following questions: a)Estimate Jπ...
  10. T

    Mass/Energy of a collapsing gas shell (MTW 21.27)

    Hi Everyone. Can anyone give me some hints which will point out how to solve this problem, particularly using 'the formalism of Ex 21.25'. I've kicked this around for a couple of weeks now and I haven't been able to come up with anything. Regards TerryW
  11. mopit_011

    Estimating the Volume of a Cylindrical Shell

    Using the equation above, I plugged in 5.5 inches for the radiu and 0.5 inches for the value of dr and then solved for the estimate of the change in volume, dV. However, the solution instead uses a value of 6 inches for the radius receiving a different estimate for the problem than I did. Is my...
  12. JandeWandelaar

    I Will a spherical mass be set in motion by a spherical shell rotating around it?

    In general relativity, rotation of mass gives rise to framedraging effects, just like linear motion does, because of the off-diagonal components in the mass-energy-momentum tensor. So around Bonnor beams there is framedragging, as well around a rotating mass. Now imagine a spherical rotating...
  13. guyvsdcsniper

    Uncharged conductor inside an insulating shell

    I worked this problem out in griffiths and my work checks out for for the potentials, b.c. and the coefficients. I will post the solutions just because my work is a little harder to read. What I am having trouble finding is the dipole moment of the conductor. I know the formula for dipole...
  14. Vividly

    I Can you solve a Disk, Washer, Shell method problem without drawing a graph?

    Is there a way to solve a Disk,Washer,Shell method problem without actually creating a graph?
  15. J

    Gauss' Law applied to this Charged Spherical Shell with a small hole

    First draw a gaussian shape outside of the sphere (a larger sphere) with radius R. The total charge from the (inner) sphere will be: $$Q = \sigma A$$ $$A = 4\pi r^2$$ $$Q = \sigma 4\pi r^2$$ Use Gauss's Law to derive electric field magnitude $$\oint_{}^{} E \cdot dA = \frac{q_e}{\epsilon_o}$$...
  16. Wrichik Basu

    Restarting GNOME shell when it has frozen, without killing applications

    Ubuntu has given me a far more stable working system compared to Windows and its buggy updates. But, once in a while, I do find GNOME becoming slow or even crashing. If I find that the GUI is becoming unresponsive, I promptly restart GNOME using Alt + F2 → r → Enter This does the job most of the...
  17. T

    A Covariant Derivative of Stress Energy Tensor of Scalar Field on Shell

    Hi all, I am currently trying to prove formula 21 from the attached paper. My work is as follows: If anyone can point out where I went wrong I would greatly appreciate it! Thanks.
  18. M

    I On the gravitational collapse of a massive shell

    Black holes form. An undeniable fact. Let's imagine a massive shell collapsing under its own weight (the exact composition of the mass is not important, so just imagine to be a continuous mass with zero thickness). What happens if the process of collapse evolves? The time on the inside will run...
  19. C

    I Average field inside spherical shell of charge

    A known result is that the average field inside a sphere due to all the charges inside the sphere itself is proportional to the dipole momentum of the charge distribution (see, for example, here). I wonder whether the same result can be applied in the case of a spherical shell of non-uniform...
  20. Shreya

    Variation of Electric Field at the centre of Spherical Shell

    My approach is thus: the shell will have induced charges if it's conducting resulting in E at the centre of shell(though flux at centre will be 0). For non conducting spheres there can be no induction only polarization of dipoles, therefore the E field at centre will remain 0. Is my approach...
  21. T

    I Observer Inside Collapsing Shell

    let's consider spherically symmetrical thin shell of dust, which is collapsing under its own gravity. There are no other forces as pressure or so except gravity, and particles of shell (dust) are in free fall. The shell has total mass M and collapse starts from rest state with diameter of the...
  22. rudransh verma

    How Do We Calculate Surface Charge Density on a Non-Conducting Shell?

    delta q=rho deltaV rho=dq/dV dq=rho4pir^2dr Then integrate dq from 0 to a because A is to be uniform in shell. Ans: A= 5.3*10^-11 C/m^2 How do we approach these problems? Looking at the answer A seems to be surface charge density. What is A? What is the direction of uniform field E. I don’t...
  23. V

    Electric Field on the surface of charged conducting spherical shell

    When I look at the relevant equations, then there is no mention of field for a point on the surface of the shell, so it gets confusing. On the other hand, I feel the radial E will get stronger as we approach the surface of shell and magnitude of E will approach infinity.
  24. V

    Magnitude of electric field E on a concentric spherical shell

    The only explanation that I have seen in textbooks is that since the outer spherical shell is symmetrical relative to internal charged spherical shell so field every where on the outer shell is same in magnitude at every point on it. I can understand that electric field needs to be...
  25. bbbl67

    I A large normal atom, but with a muon in its outer shell?

    So let's say we have a large neutral atom, e.g. gold with 79 electrons around it. Let's say we replace its outermost electron with a muon. Muons orbit closer to the nucleus than electrons, much closer. Will the outermost muon be closer into the nucleus than even its innermost ground-state...
  26. J

    Potential Inside and Outside of a Charged Spherical Shell

    So here was my first go around at it: At first it made sense in my head but don't think my process is correct. Then i noticed the example in the book: I guess the reasoning isn't 100% there in my head and if i don't have an actual σ, how will i cancel out any legendre polynomials due to...
  27. E

    Black body radiation -- Spherical shell surrounding a star

    I don't understand how this can be solved. The official solution was: F=\sigma*T^4 E=F*4\pi R^2*60*60 This doesn't make sense to me, as it seems to imply that the energy that the black body radiates depends on the radius of the shell. For a very large shell the body will reflect...
  28. Hamiltonian

    Rolling ball inside a shell problem

    I was able to solve this problem easily by using the fact that the center of mass of the system is stationary as ##\sum F_{ext} = 0## for the ball and shell system. since COM's of both objects can be replaced with point masses at there center, the shell will have maximum displacement when its...
  29. sroot

    Help with electrostatics problem (spherical shell charge distribution)

    According to my professor, the solution in this book (pages 20-21) for item (ii) is wrong: https://www.u-cursos.cl/usuario/75468645ed16a71af6da3ffd813d47f5/mi_blog/r/Problems_and_Solutions_on_Electromagnetism.pdf
  30. jaychay

    MHB Find the volume by using shell and disk method

    Can you check it for me please that I have done it right or not ? Thank you in advance.
  31. jaychay

    MHB Find the volume by using shell and disk method

    Can you check it for me that I done it right or not ? Thank you in advance.
  32. jaychay

    MHB Find the volume using shell and disk method

    Can you please help me ? I have tried to do it but I end up getting the wrong answer.
  33. E

    Finding the inductance of a rotating cylinder shell

    First, the correct answer is μ0*π*R^2. I tried to look at the cylinder like it was a solenoid, this technique was used in my class. Then I tried to find the current of the solenoid, to do that I looked at a piece of a solenoid with a legnth of dz, then: I=dq/dt=(2πRσ*dz)/(2π/ω)=ω*R*σ*dz. The...
  34. curiosissimo

    Electric field in a spherical shell

    So for the Gaussian theorem we know that $$ \frac{Q}{e} = \vec E \cdot \vec S $$ Q's value is known so we don't need to express it as $$Q=(4/3)\pi*(R_2 ^3-R_1 ^3)*d$$ where d is the density of the charge in the volume. I've expressed the surface $$S=4\pi*x^2$$ where x is the distance of a point...
  35. DaveC426913

    Newton's Shell Theorem and charge

    I've been discussing Newton's Shell Theorem re: gravity with someone, and thought of the analogy to charge. 1. I think the net effect on a negative charge inside a hollow sphere of positive charge will be zero. i.e. No net attraction. Yes? 2. But what would happen to the magnetic field if the...
  36. parshyaa

    What is the Limiting Value of Integral in Newton's Shell Theorem for r=R?

    First i tried proving Newton shell theorem directly for r=R and solved the integral as above but still got the wrong solution. Here i tried using general case: Here r' is the distance of a small ring from the point particle of mass m So my doubt is when we take r=R and then evaluate this...
  37. C

    Parameterize Radial Vector of Electric Field due to Spherical Shell

    Homework statement: Find the electric field a distance z from the center of a spherical shell of radius R that carries a uniform charge density σ. Relevant Equations: Gauss' Law $$\vec{E}=k\int\frac{\sigma}{r^2}\hat{r}da$$ My Attempt: By using the spherical symmetry, it is fairly obvious...
  38. P

    Potential of a spherical shell

    a. This solution is i can consider the charge Q as a point charge and the electric potential at a distance r is ## V = Q/(4πεοr)## b. This is where the confusion starts again when r2>r>r1, my answer ## V = ρ*4*π(r^3 - r_1^3)/(3*4πεοr) \\ V = ρ*(r^3-r_1^3)/3εοr; ## I know i am making some...
  39. Vigardo

    Weird (or not) issues in thin-walled cylindrical shell buckling modes

    Dear FEA experts, I’m trying to analyse* some finite elements model of a thin walled cylinder with variable cross-section, but I’m observing four weird issues in the buckling modes. The structure is vertically (along z-axis) and horizontally (along y-axis) loaded on top. Would you help me to...
  40. J

    Moment of Inertia: Thin Spherical Shell

    Homework Statement: Derive the formula for the moment of inertia of a thin spherical shell using spherical coordinates and multiple integrals. Homework Equations: Moment of Intertia is (2MR^2)/3 I = (2MR^2)/3
  41. E

    Electric field in a spherical shell

    Hi, been a while since I last asked here something. I am restudying electrostatics right now, and I am facing difficulties in the following question: My attempt: I tried to use Gauss' law, what I got is the equation in the capture but that doesn't lead me anywhere as I am unable to find a...
  42. maistral

    Shell diameter for ST-type exchanger equation

    Hello. I have figured out a few things about ST-type exchangers and I intend to build a reactor with this new knowledge. I have a rather... small problem. So I searched for shell diameter correlations given the pitch and number of tubes and I found this from a writeup: Apparently, it's from...
  43. N

    Ghost in the Shell (1995 & 2017)

    I watched Ghost in the Shell 1995 the other night. It was cartoon. At first I was hesitant being just cartoon. But found it so intriguing, then I rewatched again the 2017 live version staring Johansson Scarlett. I noticed the 1995 cartoon version was more well-received (Tomato score 96%) than...
  44. D

    Find the electric field inside and outside of a spherical shell superposition

    Hi! I need help with this problem. I tried to solve it by saying that it would be the same as the field of a the spherical shell alone plus the field of a point charge -q at A or B. For the field of the spherical shell I got ##E_1=\frac{q}{a\pi\epsilon_0 R^2}=\frac{\sigma}{\epsilon_0}## and for...
  45. Samanko

    Surface charge density of a conducting spherical shell

    The textbook says ' A conducting sphere shell with radius R is charged until the magnitude of the electric field just outside its surface is E. Then the surface charge density is σ = ϵ0 * E. ' The textbook does show why. Can anybody explain for me?
  46. D

    How to show that the electric field inside a spherical shell is zero?

    Hi! I need help with this problem. I tried to do it the way you can see in the picture. I then has this: ##dE_z=dE\cdot \cos\theta## thus ##dE_z=\frac{\sigma dA}{4\pi\epsilon_0}\cos\theta=\frac{\sigma 2\pi L^2\sin\theta d\theta}{4\pi\epsilon_0 L^2}\cos\theta##. Then I integrated and ended up...