Moment Definition and 1000 Threads

Hi everyone, I am honestly pretty confused as to where to start with this. Can anyone give any pointers as to where I could possibly go, for (a) and (b)? Thanks!

What is the moment for this diagram? I am getting two moments; ##M = F.S## and ##M = -F^2.S## I am getting confused.

Why is moment ##F.S## instead of ##F.\frac{S}{2}##?

I am reading a PHD thesis online "A controlled quantum system of individual neutral atom" by Stefan Kuhr. In it on pg46, he has a Hamiltonian I am also reading a book by L. Allen "optical resonance and two level atoms" in it on page 34 he starts with a Hamiltonian where the perturbation is...

Given, ##2A_P = A_Q## (cross-sections) ... (1) and, ##Y_P = 2Y_Q## ... (2) We have ##\frac {Y_P * x}{\Delta L} = \frac{Y_Q (L-x)}{\Delta L}## Using (2) in the above expression we get ##x = L/3## whereas the correct answer is ##x = 2L/3## I feel my initial idea is flawed, and that I am...

I'm Summing the Inertia of "donuts" with width dr and radius - r. I'm also "flattering" the cone into 2D and considering that each donut has different mass - because of the different height - h so: dm = 3 m h / (pi R2 H) dr I = ∫ dm r2 = 3 m h / (pi R2 H) r2 dr from triangle similarities H/R...

Calculating moment of inertia and translating it between units, I've become confused. The example is a mass of 1kg at 2000mm from the pivot. The force is applied at 1000mm from the pivot. Basics as far as I'm aware: Moment of inertia = mass * Distance to center of rotation^2 Torque = Moment...

The picture of the problem and my attempt to solve it are below. Please let me know if my resolution is correct. Thank you in advance.

The moment of inertia tensor I found out is (1/3) (-1/2) 0 (-1/2) (4/3) 0 0 0 (5/3) The principal moment of inertia tensor I found out is (1/3-I) . (-1/2) . 0 (-1/2) . (4/3-I) . 0 0 . 0 . (5/3-I) det of principal of...

I first tried to calculate the moment of inertia of the bar. The problem is that I don't understand exactly how are the dimensions of the bar. The fact that it has a width ##a## means that its height is ##a##, or that it has an unknown hight and the width is ##a##, like a parallelepiped? After...

Moment of inertia for a rod rotated around one end is 1/3ML^2 using the parallel axis theorem Moment of inertia for a sphere is 2/5 MR^2 Itotal=Isphere+Irod=2/5MR^2+1/3ML^2 However, the answer is 2/5MR^2+1/3ML^2+ML^2 Why is there an extra ML^2 added to the moment of inertia?

Now I am working with a DIY Luffing Jib Crane. Mys subcon said that: Tension of red rope for hanging a blue box load at the tip of the boom i(A) s as the same as hanging it with pulley and tied to the motor/ground_B (System in a Static Load Condition).. Blue Rope and Pulley weights are...

Dear All Masters I have problem with slewing bearing crane. My subcon made a crane that have a very high platform deck form slewing bearing. They said it is fine and the height is not an issue as it is in lower place. I know the higher the load from slewing bearing, the bigger the force or...

Homework Statement I'm a bit confused on when a force creates a moment about a point, and when it does not. In particular, in the attached diagram, would F be able to produce a moment about point A? I initially thought that wouldn't be possible as A lies on the same line as F, but since F does...

Hi, I'm looking for a simple explanation of the meaning of the crow flight distance and why it is defined as the second moment of a probability distribution: $$\bar r^2 = \int r^2 p(r)dr$$ Where ##p(r)## is the probability that a neutron is absorbed in the interval ##dr## near ##r##. And what...

Given that the tibia is 0.6kg and is 35 cm long. The force at the knee (Fk) is: (-200i + 346.41j)N Find the moment about the ankle due to Fk I found that: r: rx = (0.35cos60) and ry = (0.35sin60) Using the sum of moments where: rxFy - ryFx = 0 [(0.35cos60)(346.41)] - [(0.35sin60)(-200)] =...

Homework Statement For a configuration of charges and currents confined within a volume ##V##, show that $$\int_V \mathbf J d \tau = \frac {d \mathbf p}{dt}$$ where ##\mathbf p## is the total dipole moment. Homework Equations ... The Attempt at a Solution I have one question: since the...

Hey there! I am working on a project concerning the mathematical modeling of nano-swimmers in a viscous medium. Assuming the nano-swimmers to be cantilever beams, the project involves calculation of moment of inertia of the said nano-swimmers. While calculating the moment of inertia of a simple...

Hello. This is a basic statics/mechanics of materials problem. Here's an image of my work. I've taken a course in statics before, and this is supposed to be review, but I can't seem to get the correct answers which are V_c = 75 lb, M_c = 1125 lb*ft. I've chosen the right side, and it seems as...

Hello there! I'm trying to check the first order (1 loop) correction to the electron magnetic moment. I'm following Schwartz and Peskin, but both of them have a point where they hide the calculations, and I'm not sure if my calculations are correct. The point is exactly this: I don't know...

How to prove the dipole moment of an isolated quantum system in isotropic space is identically equal to zero, unless there exists an accidental degeneracy. Thanks in advance

1. Having really hard time understanding the concept of moment and equilibrium in statics. In the following picture the man is carrying a 6kg uniform rigid board. I'm asked to calculate the amount of force the man feels on his shoulder. (at point A) Now I know I'm supposed to start by making...

A bar magnet will have a definite magnetic dipole moment, irrespective of the presence of an external field. Why is the moment, then, always defined in relation to the torque it would feel in an external field? Is there any other definition for the same?

Homework Statement https://cdn.discordapp.com/attachments/373928512811302912/528638926148337704/question.PNG part a )50N I cannot answer part b. Homework Equations M=FD The Attempt at a Solution Ok so if both pivots were in contact with the beam I would just equate them with the oppposite...

Hello, It is well know that the moment of a force ##F## depends on: a) the force magnitude ##|F|## b) the choice of the moment reference point ##P## c) the distance (lever arm) from the point ##P## to the point of application of the force ##Q##. That said, an object with a single force applied...

I am trying to derive the equation ##\vec{\Gamma} = \vec{m} \times \vec{B}##, where ##\vec{m} = I \vec{A}## is the magnetic moment, and ##\vec{A}## is normal to surface ##A##, from the Lorentz force law ##\mathrm{d}\vec{F} = I \vec{dl} \times \vec{B}##. For an arbitrary closed current loop ##C##...

Hello, I am learning about the pitching moment acting on a wing that is immersed in an airflow hoping to clarify some key concepts. In general, the moment of a force depends on: Location of moment reference point ##o## Force magnitude Lever arm (distance between force application point and...

Homework Statement Hey, just wanted to ask a quick question about how to find the moment of inertia of two rods (of equal mass and length) attached together in a T shape (the axis is at the bottom of the vertical rod). My calculations got the correct result but I just wanted to check whether my...

I was thinking that if a uniform rod of mass M and length L remains static ,then it's centre of mass will be at L/2 from one end (e.g total mass assumed to be concentrated at L/2 ) But if this rod is moving with uniform angular velocity ω about an axis passing through it's one end and...

Homework Statement A vertical retaining gate 2metres X 24metres hinged about the bottom edge of a dry dock has water to a depth of 21 metres on one side. Calculate the Retaining Force at the middle of the free upper edge of the gate to keep it shut in the vertical position. With the density of...

Hi, I'm having trouble understanding angular moment of the one electron hydrogen atom. Solving Schrodinger equation on a referece system (say S) I get the energy eigenstates. They depend on three quantum numbers, n, l, m \frac{-ħ}{2 m}\nabla^{2} \Psi - \frac{e^{2}}{4 \pi \epsilon r} \Psi =...

Homework Statement Posted Photo with Work done so far, but my MOI is off Homework EquationsThe Attempt at a Solution

Hello! I am reading Schwarz's book on QFT and in chapter 17 he introduces the anomalous magnetic moment. I am not sure I understand a step in the derivation (from a mathematical point of view), when going from 17.23 to 17.24 (I attached a SS of it). I was able to get certain terms, but I am not...

I know that total magnetic moment of an electron (I am not sure if it is magnetic moment of electron or atom, please clarify this) is sum of magnetic moment caused by orbital motion and spin angular momentum. So, Total magnetic moment = Orbital magnetic moment + spin magnetic moment Do I have...

When a question only asks for the moment of inertia (of say, a T-section), do I have to find the moment of inertia with respect to both the x and the y axis?

Homework Statement A 23 kg solid door is 220 cm tall, 95 cm wide. What is the door's moment of inertia for rotation about a vertical axis inside the door, 17 cm from one edge? Homework Equations I = I_cm + MR^2 The Attempt at a Solution I = I_cm + MR^2 I = (1/12)(23kg)(0.95m)^2 +...

Homework Statement A 15-cm-diameter CD has a mass of 21 g . What is the CD's moment of inertia for rotation about a perpendicular axis through its center?Homework Equations I = (1/2)MR^2 3. The Attempt at a Solution I = (1/2)(0.21g).((15/2)^2) = 5.9*10^-4 kg*m^2 cant see what I am...

So I need to find equations for the force required to tip over a cylindrical object. This is fairly straight forward in the case when the force is applied above the centre of mass, by taking moments about the pivot corner. However, in the case where the force is applied below the centre of mass...

Homework Statement The ammonium ion NH4+ has the shape of a regular tetrahedron. The Nitrogen atom (blue sphere) is at the center of the tetrahedron and the 4 Hydrogen atoms are located at the vertices at equal distances L from the center (about 1 Å). Denote the mass of the hydrogen atoms by Mh...

Hi all I was hoping someone could remove some doubt in my mind with regards to interpreting the Second Moment Of Area and Eulers formula for buckling. Am I correct in thinking that:- - The higher the Second Moment Of Area Value the more resistant to bending. - The lower the Second Moment Of...

Hi all I was hoping someone could help explain the difference between Young's Modulus and Second Moment of Area. I know that Young's modulus is a measure of how elastic a material is and is calculated by Stress/Strain. I know that the Second Moment of Area can be defined as a objects...

I'm interested in understanding how to deal with a torque applied to an angled cantilever beam. The torque is being applied along a horizontal axis at the location of the end of a cylindrical beam. I am interested in how this torque will cause twist along the beam's axis, as well as any...

Dipole problem (which is solved through mirror imaging) has been troubling me with its solution. I understand everything except how the dipole moment's coordinates came to be, since when converted into x-y axis, its doesn't make sense. (problem 4.6) The screenshot contains the solution which...

Homework Statement Compare Dipole moment of CH3F and and CD3F where D is deuterium. Homework Equations Theory questions The Attempt at a Solution Our sir had explained that to do this question we muat take into account the vibration of the atom in the respective molecule. That is that the...

Homework Statement Homework EquationsThe Attempt at a Solution i just don't know from where to take the R which is colored with brown, in the 2(MR^2), what is the R here exactly, because i took the radius of the sphere , but i get different answer althought it's near.

I had a test today on my linear algebra class, and it's safe to say that I didn't get more than a seventy percent on it. I got the first two problems of the test down, but the last problem asked me to prove something involving linearly independent sequences, how if a vector isn't in the span of...

Homework Statement For my question, I am following a previous method I used in my HNC where I had to determine the position and magnitude of the maximum bending moment. I am now working on my project and I have revisited this question but I am having some issues in my method. The above diagram...

Homework Statement I was asked to find the shear force diagram and bending moment diagram for this load combination...But , i have problem of getting the BMD now . i am not sure which part is wrong , can anyone point out ? Homework EquationsThe Attempt at a Solution MA = 5(2)(1/2)(2/3 x 2) +...

I was just looking at indeterminate statics problems where you have a beam, three elastic wires (left, centre, and right that are holding it up), and some extra mass. (Just like example 5 in the notes below: http://fast10.vsb.cz/lausova/indeterm_all.pdf). I understand the method that was used to...

Homework Statement Homework Equations Singularity equations for beam deflection $$\sum M_B=0=-M_0-R_AL-M_0$$ $$R_A=-\frac{2M_0}{L}$$ The Attempt at a Solution I know how to use singularity equations and all that but my problem is calculating the force especially when moment is involved. For...