Moments Definition and 626 Threads

Does any moving charge generate a magnetic moment? I thought so because a moving charge generates a magnetic field.

What formula do I need here?Starting from the sum $I = \sum\limits_{\alpha = 1}^Nm_{\alpha}\rho_{\alpha}^2$ and replacing it by the appropriate integral, find the moment of inertia of a uniform thin square of side $2b$, rotating about an axis perpendicular to the square and passing through the...

Homework Statement I'm not sure on the principles of moments Homework Equations The Attempt at a Solution Is it just that moments are a turning force?

Moments -- Balancing a weighted meter stick A meter stick is found to balance at the 49.2cm mark when placed on a fulcrum. When a 46.0g mass is attached at the 14.7cm mark, the fulcrum must be moved to the 38.7cm mark for balance. What is the mass of the meter stick? I know I have to use...

Thinking about Newton's laws, one can see that they concern the force and the torque (the first moment of the force) acting on a particle. That is enough to describe translation and rotation. But, is there something more to this? What about second and higher moment of the force? Is there any...

Homework Statement A uniform sphere rests on a horizontal plane. The sphere has centre O, radius 0.6m and weight 36N. A uniform rod AB, of weight 14N and length 1 m, rests with A in contact with the plane and B in contact with the sphere at the end of a horizontal diameter. The point of...

I'm working through my professor's solution for this problem, and I don't understand how he comes up with the reaction force at B without taking into account the moment at B. Any help would be greatly appreciated. http://img832.imageshack.us/img832/6953/sibi.png

Homework Statement Find the center of mass of a lamina in the shape of an isosceles right triangle with equal sides of length a if the density at any point is proportional to the square of the distance from the vertex opposite the hypotenuse. Homework Equations ∫∫ (f(x,y) dA mx= 1/m(∫∫...

Homework Statement The picture of the beam below has a module of rigidity EI, determine the reactions at the supports and the equation of the deflection curve of the left half of the beam Homework Equations v*EI=((Ma*x2)/2)+((Ra*x3)/6) Ʃ of Forces in Y direction = Ra+Rb=0 Ʃ Moments...

Hello, My friend and I have been having a discussion about moments (when applied to a chest of draws). The argument is; if the weight in each draw is the same, and anyone draw is opened fully, will a draw higher up be more likely to cause the chest of draws to tip forwards, or are they all...

Homework Statement Let X_1,...,X_n be iid with pdf f(x;\theta) = \theta x^{\theta-1} , 0 \le x \le 1 , 0 < \theta < \infty Find an estimator for \theta by method of momentsHomework Equations The Attempt at a Solution I know I need to align the first moment of the beta distribution with the...

I was wondering if there were any mechanical engineers that can answer a few questions I have regarding an assignment that I have been set. We have to choose a suitable beam to support a monorail. we are looking for a moment of deflection of around 10mm. Using the universal beams table bs 4 1993...

Two painters of mass 50kg and 70 kg stand on a uniform horizontal plank ABCDEFG of mass 40kg and length 8m. B, C, D and E are respectively 1m, 2m, 5m and 6m from A. The 50kg painter stands at B, the 70kg painter at D and the plank's supported at C and E. Find the reaction at each support I...

Homework Statement So the problem starts out like this Stick of the Gods! You hold one end of a stick, but it has no other end. It simply extends into infinity. Its one-dimensional density distribution is given by: λ=(λinitial)times(e^(-x/L)) λ is the density The problem doesn't state what...

Homework Statement The ceiling-mounted bicycle rack (shown in "Capture" image in attachments) with dimensions p = 50 mm, q = 1000 mm and r = 150 mm for a bicycle that weighs F = 200 N. The rack is to be made from two parts, ABC and BD, cut from a steel tube and then welded together at B...

Homework Statement The T-beam is loaded as shown in Figure attached Find the maximum transverse shear stress at the location of the maximum bending moment. Homework Equations Forces in Y direction = 0 for it to be in equilibrium Moments about a point = 0 for it to be in equilibrium...

What are they? I have some poeple telling me that for a cylinder it's I = (1/4)MR2 + (1/12)ML2 and that for a disk it's the same. Other people have told me that it's I = (1/2)MR2 for a disk and that it's the same for a cylinder. In the past I've used the former and have gotten the right answers...

Homework Statement For any random variable X, prove that P{X\geq0}\leqinf[ E[ phi(t) : t \geq 0] \leq 1 where phi(t) = E[exp(tX)] o<phi(t)\leq∞ Homework Equations The Attempt at a Solution I am not sure how to begin this. Any hints to get started would be greatly appreciated.

Homework Statement The image in the attachment shows two uniform ladders (red and blue) in equilibrium resting on grass(green). The distance between A and B is "L" units. The two ladders are freely hinged at C. Because the ladders are uniform their Centers of mass lie at their mid...

Homework Statement A flagpole of mass 25kg and length 2.5m is held in a horizontal position by a cable at 30° from the end of the pole. The centre of gravity is 1.5m from the fixed end. Determine: 1. the tension in the cable. 2. the vertical component of the force at the fixed end...

Hello, I was solving a vector & moments question as a part of my revision and got stuck somewhere. I really need your help.. some sub-questions are solved, please correct me if I'm wrong. Here's the question (Its kinda long) : The free-body diagram shows three forces that act on a stone...

Homework Statement Here is the problem: Here is the solution: I am confused about part c. The Attempt at a Solution Here is my attempt at part c: I don't get why the answer key solution sums the moments about point G. I decided to sum up the moments about C and D and...

The underlined red part: I don't particularly understand where they got this from? The yellow highlight: Why are they finding the vertical distance, instead of the perpendicular distance?

Homework Statement The problem is to find the moments E(X^k) of f_x(x) = (\theta+1)(1-x)^\theta, 0 < x < 1, \theta > -1 Homework Equations E(X^k)=\int_0^1 x^k (\theta+1)(1-x)^\theta dx According to Mathematica, the solution is \frac{\Gamma(1+k)\Gamma(2+\theta)}{\Gamma(2+k+ \theta )}. I...

Homework Statement Here is the question along with part of the solution. I am online concerned about finding the force at C. The Attempt at a Solution For my solution I decided I would sum the moments about point B. However I ended up getting the wrong answer for the force at...

Homework Statement The crane below is on level ground. The x-axis is through the contact points of the rearmost wheels with the ground, the y-axis is parallel to the front-to-back centerline, and the z axis is vertical as shown. The bed (platform) of the crane is 3 ft above the ground. For...

Homework Statement Find the components of the force at D and C using moments picture attached Homework Equations M=F x r The Attempt at a Solution I'm really stuck on this one. The force from the 70 kg weight is 70*9.8 = 686N, so F=-686j. I found the moment about point C...

For some reason I found myself wondering why we never talk about the contribution to the magnetic properties of materials due to the nuclear spins; we only ever worry about the electrons. After a short while I remembered that the magnetic moments of protons are vastly smaller than electrons (and...

Hi I am reading about quantization of orbital angular momentum and, as I read, I am trying to compare it to the theory I already know on how atoms behave in magnetic fields. Here is the situation so far (I only look at 1-electron atoms to keep it simple for now): I assume the quantization...

I cannot seem to get the first moment of Poisson's distribution with parameter a: P(n_1)=\frac{a^{n_1}e^{-a}}{n_1!} when using the characteristic function \phi _X (k)=\exp [a(e^{ik}-1)]. The definition of the first moment involving the characteristic function is <n_1>=\frac{i}{n} \frac{d \phi...

Homework Statement Write code to calculate the input impedance on a thin wire antenna using the below form of Pocklington's integral equation. Use Method of moments. Use a pulse as the basis function, point matching and delta-gap generator as the 'source'. Assume the wire is broken up into 7...

Homework Statement A uniform ladder AC weight 400N & length 3.5 m is held horizontally by 2 people. One person supports at A and the other at B, a distance 1m away from C. 1. Calculate the supporting force provided by the person at A. (I managed to do this one and the answer is 120N) 2. The...

Hey guys, I am trying to understand the concept of mathematical moments (as defined in this wikipedia page: http://en.wikipedia.org/wiki/Moment_%28mathematics%29), as some work I am doing relates to them. I am looking for more information to read up but when I search maths moments I get...

There are three compounds: 1.) fulvene 2.) calicene 3.) I don't know the name of the third compound. It looks like calicene except that there is not a double bond inside of the three-membered ring. Anyways, it turns out that fulvene and calicene have unusually large dipole moments...

Dear all, Sorry to post this question in this section again. I am currently looking into few static analyse algorithms. I noticed that they are analysing with different order moments or cumulants to analyse the data. I guess it is because these algorithms are focus on different aspect of...

Homework Statement Three forces are applied to a locked pulley. Determine the magnitude and direction of the resultant of the three forces and the perpendicular distance from the axle of the pulley to the line of action of the resultant. **I'm unable to upload a photo of the pulley at the...

Hi, can someone who is familiar with the analysis of random walks (statistical mechanics, condensed matter physics etc.) help me on solving a particular problem? We define the following random walk, the random variable w(t) is evolved as w(t+1)=w(t), with probability of...

Hello everyone I have some problems figuring out the correct way to calculate my rigid body angle based its local moment. I am working in R3 space. I have the rigid body local rotational acceleration expressed as a function of distance to fulfill a rigid body constraint: AlphaL = F(x,z)...

Homework Statement Hi I am having tough time figuring out how to determine normal stresses σx, σy, σz using the flexure formula. All that confuses me is which moment to take for which σ. My for σx or Mz for σx and so on.. I will post an example question. In the question below, find the...

I have this mass-spring-ball system: https://dl.dropbox.com/u/1723401/massa-molla/sistema.png There is friction, but the ball only rolls. I have to find the model of the system. I started to divide the 2 systems and for mass1 I found the follow equation: m_1 \cdot \ddot{x_1} = F_k...

(a) The moment the force, F, makes about O is 15 N-m clockwise, and θ = 30˚, find the magnitude of F. (b) If the force F = 100 N, determine the angle θ so the force develops a clockwise moment about point O of 20 N-m. Limit your answers to a range of 0º ≤ θ ≤ 90º. I'm a little lost can...

I’m having trouble getting my head around this example and solution that was given as part of a revision pack for an upcoming exam. Any explanation would be gratefully received. Question: A simply supported regular I beam is 90mm wide and 120mm high. The top and bottom flanges are 10mm...

1. How do you calculate the maximum moments in a 2-span continuous beam? 2 span beam with 2 different uniformly distributed loads (UDL) at different spans: i46.tinypic.com/2d7zpw.jpg I am a first year civil engineering student. This is apparently a statically indeterminate structure with one...

Why doesn't taking moments about an axis passing through point A or B work? Why must it be the center of mass here?

Hi, I've been working on a tubular sub frame, that I want to attach to a main frame. The attached shows the sub frame in black lines. The main fram is in purple. There are only four connection points and a force pushing down on each side. When I check for the reaction forces and make...

Hello I am having trouble understanding a concept of what force i have found and how i can maniplate this data. I have attached image of a triangular frame which has a 10Kg mass hanging from it at one point. I know how to calculate the Force Fh using moments. i am unsure what this force...

[b]1. Sphere inner core radius 3490km and density 13000kg/m3. Outer radius 6400km and density 4000kg/m3. Show that the moment of inertia is approximately 8 x 1037kg m2. [b]2. I know that the moment of inertia of a sphere is 2/5xmr2. [b]3. I have calculated the volume for each part...

Hello all can anyone advise me if i am doing this right, i have a 3m bar supported at both ends at 1m in 5kn and 2m in 10 kn, i understood that moments A = 1x5 and 2x10 =25/3 and support A upward force 8.3kn and B 5+10-8.3 = 6.7kn? anyhelp would be great thanks

Hi, I'm studying quantum mechanics and statistical mechanics, and they make heavy use of the 'correlation functions/green's functions' which are merely the moments of the distribution of some variable. I have very intuitive understanding of moments and cumulants in terms of the distribution...

if i have two forces acting at two different angles at a same spot will the addition of the moments of the two forces be the same as the moment whereby i take the net force of the two forces and get the moment of the net force of the same two forces? is there a way to explain why for the same...