Moment Definition and 1000 Threads

Hi, I wasn't sure if this is more Physics/Astro or chemistry because its actually all 3. i've got some conceptual issues with some tasks at hands, and was wondering if anyone could clear that up for me. (These questions are all regarding molecules) 1) How do you create a potential energy...

Homework Statement Taylor, Classical Mechanics Problem 10.11 ** a) Use the result of problem 10.4 (derivation of the general integral for a moment of inertia of a continuous mass distribution in spherical coordinates, using point particles) to find the moment of inertia of a uniform solid...

Homework Statement I'm just looking for the proper equation to use to find the moment of inertia of a complex assembly of bodies. I'm not a student and this isn't homework, but it seemed the most relevant place to pose the question. One of my hobbies is making toys and I'm trying to calculate...

Homework Statement The problem is a cantilive beam of length L with a triangular uniform load or W. The solution is to find the slope and deflection at the end by moment area method. My solution is not matching the textbook solution of wl^3/8EI and 11wL^4/120EI Homework Equations First...

Hi, I am trying to wrap my head around what happens when a ball of mass m bounces against a hard floor. I assume a system that includes the ball and the floor (and eventually the entire planet) and an elastic collision. Before the ball hits the floor it has a momentum of mv. After the bounce...

Problem - The T-shaped bracket shown is supported by a small wheel at E and pegs at C and D. Neglecting the effect of friction, determine the reactions at C, D, and E when the angle is 30 degrees. I have taken the moment about E, and gotten a result for all the reactions. However, in the...

Homework Statement A sphere with radius R = 0.200 m has density ρ that decreases with distance r from the center of the sphere according to \rho = 3.00 \times 10^3 \frac{kg}{m^3} - (9.00 \times 10^3 \frac{kg}{m^4})r a) Calculate the total mass of the sphere. b) Calculate the moment of inertia...

I've to work out b & d in this equasion. I=bd^3/12 I know that the ratio between b & d in this case is 1.166 and I am given the value of I. It is an engineering problem as the software will only allow the use of square/rectangular or round section but we are using H section and we are allowed...

Homework Statement A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 16.0 m/s. The cliff is h= 41.0 m above a flat horizontal beach h=41 g=10m/s vi=0m/s vf2=vi2+2gh vi=28.64 h=vi+vf/2xt 41=28.64/2xt 14.32 t=2.86 28.64x28.64, 16x16 Square...

Derive the following expressions for ux, uy and uz: ux(t) = ux(0) cos(wo t) + uy(0) sin(wo t) uy(t) = - ux(0) sin(wo t) + uy(0) cos(wo t) uz(t) = uz(0) wo is angular frequency. wo = g Bo Homework Equations wo of this precession is proportional to Bo u and J have the same orientation: u = g J...

Homework Statement The problem shows a wrench with a force being applied to one end. Rotation will occur around point P at the opposite end. The force is applied 43 inches to the left from P, and 6 inches above P. The angle theta is between the vertical axis at the end of the wrench (non-p...

Homework Statement A ceiling fan consists of a small cylindrical disk with 5 thin rods coming from the center. The disk has mass md = 3.3 kg and radius R = 0.26 m. The rods each have mass mr = 1.2 kg and length L = 0.72 m. What is the moment of inertia of each rod about the axis of rotation...

Moment of inertia is I = MR2 object has more mass means more inertia and less mass means less inertia. That means moment of inertia is directly proportional to mass. But how the moment of inertia is directly proportional to the square of the distance.?

Homework Statement A solid cube of wood with side 2a and mass M is resting on a horizontal surface. The cube is constraint to rotate about a fixed axis AB. A bullet of mass m and speed v is shot at the face opposite ABCD at a height of 4a/3. The bullet becomes embedded in the cube. Find the...

With a Poission random variable, we know that \(E[X] = var(X) = \lambda\). By definition of the variance, we can the second moment to be \[ var(x) = E[X^2] - E^2[X]\Rightarrow E[X^2] = var(X) + E^2[X] = \lambda(1 + \lambda). \] The characteristic equation for the Poisson distribution is...

Does an electron really spin about its own axis? If not, what does spin magnetic moment imply? My physics teacher said "Besides the orbital moment, an electron has an intrinsic magnetic moment, it is called the spin magnetic moment, But I hasten to add that it is not as though the electron is...

Im needing to calculate the Zxx and Yxx for 2 shapes. The shapes are an H profile and a + profile however its not the basic profiles I am needing but the moment of inertia for the weld profile surrounding them as the theory is they are welded to a vertical metal surface then a load is applied...

Hi, it's been quite some years since I took some entry-level mechanics at uni, and my book is no longer with me, so I'm struggling a bit here. I'm making a very simple rigid body simulator just for fun, but the angular velocity is not working out right. I suspect I've forgotten something...

Homework Statement Find the moment about point A Homework Equations The Attempt at a Solution Calling counter-clockwise positive (300N)(1m) + 500cos(30)(.2) - 250(4/5)(.5) = 286.6Nm Not the correct answer. What am I doing wrong?[/B]

http://postimg.org/image/onxjqc26l/ I have found the shear stress of the inner cylinder to be 405 Pa like in the solution but I am having trouble visualizing the total moment of this stress about the center line. I was wondering if someone could explain where that d(theta) in the moment...

Problem: Consider an ice skater spinning in a circle. We will approximate the body as a cylinder with a radius of 0.25 m. The total mass of the skater is 50kg. When the skater has her arms extended we will approximate her body as a cylinder with two rods attached. Each arm is 0.75 m long and has...

I have attached both the question and my attempt at solution. My problem is reducing the equation further to get the value of a/L

A small confusion ! Why is most of the mass of the wheel concentrated on the rim ? I know that it is to increase the moment of inertia , but what is the practical use of doing so ? Thanks in advance !

Homework Statement An electrical engineer in your semiconductor company is working on a design of an electrical contact with a Si wafer. The electrical contact is in the form of a thin Cu “finger” touching the back side of a wafer as shown below. The electrical engineer claims that he is...

Hi there, I have been given this question, and I have not even the slightest of clue's where to start. I know angular velocity is equal to ω=v/r But besides that I have no idea. Where can I start?

Homework Statement I have a 5m long simply supported beam, with supports at points 0m and 5m. There's a UDL of 10kNm^-1 from 0m to 4m. It has downward forces acting at 2m (10kN) & 4m (15kN). I need to sketch a bending moment diagram to determine the position & value of the max bending...

Homework Statement "A molecule has its dipole moment aligned with a 1.8 kN/C electric field. If it takes 3.5x10^(-27) J to reverse the molecule's orientation, what is its dipole moment?" Homework Equations Potential energy of dipole in an electric field U = -p*E = -p*E*cos(theta) U...

Homework Statement (a) Calculate the maximum bending moment (b) Calculate the maximum stress in the beam (c) At the point of maximum stress sketch a graph of the stress distribution through the thickness of the beam, indicating which are tensile and compressive stresses. (d) Determine the...

For a uniform, hollow cylinder, why is this derivation wrong? M = mass of whole solid cylinder m = mass of missing cylindrical piece R = radius of whole cylinder r = radius of missing cylindrical piece moment of inertia = moment of inertia of whole cylinder - moment of inertia of...

In one moment in time you have a charge going about in a circle of radius r. in another moment in time the charge goes in the same circle but faster, where Δv is the difference in speed. i want to find the change in the magnetic dipole moment Δm.if magnetic dipole moment m=IA (assuming uniform...

Hi, I have been trying to get the expression for the transition dipole moment of hydrogen but I am not able to get the expression. Hope someone can help me with that. I want to evaluate \vec{d}(v)=<v|\hat{r}|0> where v is the free state and 0 is the 1s wave function for hydrogen...

Homework Statement Write the integral that would define the mgf of the pdf, f(x) = \frac 1{\pi} \frac 1{1+x^2} dx Homework Equations The moment generating function (mgf) is E e^{tX}[\itex]. The Attempt at a Solution My question really has to do with improper integrals. I must...

The Question : A cylinder of mass M , and moment of inertia around its center Io, is initially rotating around its central axis with angular velocity wo. İt is gently placed on a homogeneous thin plate of mass m which rests on a smooth horizontal surface. Assume that the plate is sufficiently...

I would like to know if there is any proof as to whether the moment of inertia for two bodies (the masses of each body are distributed on a line) about their respective center of masses, is strictly different. If not, can anyone provide me a link to where the work is computed.

Homework Statement I found the moment of inertia of a rectangle, with the axis perpendicular and going through the center using double integration. But I also used what i thought to be an equivalent method, but it didn't work.Homework Equations dI=r^2dm \int dI The Attempt at a Solution I was...

1. Question: What is the moment of inertia of a thin, flat plate in the shape of a semicircle rotating about the straight side (Fig. 12.28)? The mass of the plate is M and the radius is R The diagram is attached for reference. Homework Equations Moment of Inertia: I = ∫R2dm...

In the Stern-Gerlach experiment, we have an inhomogeneous magnetic field aligned with the axis labeled z. The two distinct deflections are caused by the force from two distinct magnetic moments \mu = \gamma S. I understand that the spin larmor precesses around the field and that the expectation...

Homework Statement Let ##X_1, X_2, ..., X_n## be a random sample from ## f_θ=2x/θ^2## , ##0≤x≤θ##. Find a maximum likelihood estimator for θ. Find the method of moment estimator for θ. The Attempt at a Solution I have already found that the MLE is max{##x_i##}. I just need to find the...

Are there any experiments or theories about the relation between magnetic dipole moment orientation and velocity vector of free electrons?

This is my first time posting in this site so if I left out any information or the information needs to be formatted differently I apologize ahead of time. Homework Statement Determine the moment of inertia of the area about the y axis. The curve is represented by y2=2x, and the shaded...

What does the term magnetic moment mean and how to look at it intellectually .what are its effects,what are its type

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Definition/Summary Moments of area are properties of rigid bodies, they depend only on shape and not on density, and they are scalars (numbers), and are measured relative to a particular axis. First moment of area measures a body's resistance to shear stress along an axis. Second moment...

Hey all! I think I have the problem within my grasp, just would like a second opinion to help me cross the finish line... Homework Statement Consider the following diagram of the bottle holder assembly (see attachment). The weight of the bottle is 11N, and the weight of the board is...

What is meant by moment of particles ? Why the algebraic sum of moments of all particles about centre of mass must be zero ?

Why the torque is called moment of force and angular momentum is called moment of linear momentum ? Please explain.

Good morning PF, I am having some difficulty finding info on calculating a composite moment of inertia. The section I am working with is 8 separate columns (WT5x15) arranged evenly spaced around the circumference of a circle. You can see what I'm taking about in the attached jpg. I found...

This is a problem from Michael Lindeburg's FE Review Manual. It is in Chapter 20, Number 11 if you have the book. PROBLEM: There is a picture of a cantilever 2 m in length attached to a wall. There is a force applied at a 30 degree angle from the horizontal at the free end of the beam...

hi pf! so i am going to take the skewness and kurtosis of a sample. however, if i already have a pdf, is there really any reason for doing this? thanks! josh

Homework Statement since it's asking us to find the moment of inertia with respect to y-axis, why did they draw the differential element to x-axis? Homework Equations The Attempt at a Solution because of the initial problem.. i don't know how to start.. so dA = x dy I(y) =...