Moments Definition and 626 Threads

Homework Statement Two plasterers Bill and Dave of mass 45kg and 65kg respectively stand on a unofrm plan ABCDEF of length 4m and mass 40kg. The plank is supported at C and E where C is 1m from A and E is 1m from F. Plasterer Bill stands at B which is 0.5m from A and plasterer Dave stands at D...

For my statistical mechanics class I need to find the cumulants of a special distribution of which all moments are constant and equal to a. I followed two different approaches and obtained imcompatible results, something is wrong but I couldn't figure it out. Here's what I did: Since all...

First time posting hi guys and thanks for the help before i even start :) here goes, i am on question 4 and I am not the best with this but to be far i am not 100% sure on the question here goes An aircraft flies throught still air at a velocity of 100ms-1 due East. However due to a wind...

Homework Statement Consider the Hydrogren atom in a magnetic field of 2T. If the atom is in the ground state (orbital angular momentum L=0) a) Write down the magnetic moments of the proton and the spinning electron b) What is the splitting of the energy of the ground state in eV due to the...

Homework Statement See attached file Homework Equations M_A = Fd The Attempt at a Solution I using the above equation..just summing all of the forces and their directions but I keep getting the wrong answer(distances from the moment). I also tried summing all the forces from...

If the sum of all moments about a point A of a body is 0, will it then be 0 anywhere else on the body? (I'm working in 2-D)

1. How can turning moments be applied in everyday life? It may be advantageous to give worked examples in each case. 2. Can I use wheels & wrenches as examples? Can you please give me more examples? 3. I really don't know what examples I could work from the wheels and wrenches.

Personal experience, hearsay, unsupported rumors, famous examples, what are the best examples of "making do" with inferior, or an eclectic and seeming useless selection of parts to successfully solve a real problem? http://en.wikipedia.org/wiki/Rube_Goldberg_machine Probably one of the best...

Moments of Inertia--Big Confusion Hey, 1. Using the conventional method to calculate moments of inertia of rigid objects which says we should divide the object into small pieces each of mass dm and then calculate the integral. is it an exact calculation or an approxximation? so far my...

Can anyone give me ideas/hints on how I should go about this?

The moment of inertia about an axis along the length of a rod is zero, correct?

Hi, I'm in the middle of programming an inertia system and am only really just starting to appreciate what the heck inertia is :) I have been taught inertia, but I haven't actually applied it in a real situation (all my exams and tutorials have resulted in formulae giving answers like...

Please could someone tell me how to work out the attached moments question as I've really no idea how to do this one. I'd be really grateful for any help. Thank you. Cathy

Please find the attachment below. Thanks

Well...I am able to work the problem just fine on the x' and y' axes using the standard vector analysis of r X F, I just have no idea how to transfer it to the x and y axes. I provided a picture of the actual problem, alongside the actual answer in the solutions manual. I don't understand...

Ok I have this question where there is a beam 12m long, there is a pivot 3m along the beam (A) and another 10m along the beam (B). There is an elephant at the left end of the beam that weighs 10,000N and the weight of the beam is 4000N, I need to plot a graph of the distance moved (m) against...

It can be shown that if a hamiltonian is invariant under space inversion and if an eigenstate is non-degenerate, then the state is either even or odd in each position coordinate. So if there is a perturbation given by a uniform electric field, which has: H_1 = - \vec E \cdot \left( \sum_i q_i...

When trying to understand moments...two particular things bother me. First Question First...if the unit for moment is defined as a force x distance, a Newton-Meter perhaps, what the hell does that mean? A Newton is very self explanatory...the amount of force needed to accelerate a...

A roller whose diameter is 1.0m weighs 360N. What horizontal force is necessary to pull the roller over a brick 0.1m high, when the force is applied (a) at the center, (b) at the top of the roller. I need a diagram showing the forces acting at the point of contact between the roller and the...

Funniest video! http://www.metacafe.com/watch/129909/family_guy_osama_bin_laden/

The books said that total magnetic moment of an electron is spin + orbital magnetic moment. But is the orbital magnetic moment realistic quantum mechanically? I thought electrons dosen't have a trajectory. The Stern Garlach experiment showed that silver atoms only split into two paths after...

How often do you have them? You know those moments when you have been blindly banging your head against that wall when all of a sudden the wall disappears and you have a moment of satisfying clarity. Understanding ( or at least the illusion or temporary understanding ). What was you latest...

Hello, This is probably really simple but i don't know if this is the right way to work out the answer i have attached an image containing the problem. I know how to get F2 : Taking moments about A: F2 Cos 60 = 1500 F2 = 3000N But then it says to find F1 using the principle of...

Hey! My teacher gave me a very challenging problem on QM. I've only had one introductiary course, but he said he wanted me to figure this problem out by using whatever resources, so now I turn to you guys ;-). The problem is the following: London attraction forces can be thought of as...

I'm in an aerodynamics class, and I have this canard configuration I'm trying to figure out for a final exam. I need to find the sum of the moment about the center of gravity. I may cannot be helped without the drawing being posted. So far this is what i have: Mcg = Mac - (lcg + lw)Lw +...

I've attached a screenshot of the question. This is what I've tried so far: I've calculated the initial energy of the system (which is all potential energy): Energy of disc: 0.5*I*w^2 + 0.5 *m*v^2 + m*g*h = 0 + 0 + 0 Energy of arm: 0.5*m*v^2 + m*g*h = 0 + 4*9.81*1.5Cos(45) = 41.62...

Hello all, Since I have run into the problem of regularly leaving moments out of my free body diagrams (and vice versa), I thought I'd pose a question on the topic. In trying to wrap my head around the concept, I've gone back to the beginning of the semester's notes and that didn't really...

Hi everyone. I have this problem and I don't even know how to start it! If you are familiar with my previous posts, you know that I usually have most of a problem completed before posting here with my difficulties, however, I cannot even start this one! I don't think there is enough...

This question is bugging me and though from my point of view it doesn't make sense I'm hoping that someone else can see my thinking and tell me whether they agree with it or not (because this is about the fourth question I've had to say that I can't solve this because the book is talking BS)...

Derivation of the principle of moments... i know the principle of moments might seem very obvious at the beginnning... but really, how was it derived or proposed? and by what proof?

Blard: Consider the hydrogen atom in a magnetic field of 2T. If the atom is its ground state. (a) Write down the magnetic moments of the proton and the spinning electron. A: For electron Uz = +/- 0.5gUb = - 9.27E-27 J/T Since it's the ground state g is 2 (approx) My question is what...

can anyone tell me how to find moments of inertia for the centre point of a semicircle??

When you calculate the two moments for the law of the levers, they are supposed to be the same, right?

Hello everyone, I'm working on a basic spaceflight simulator during the break, and I've been unable to come up with some info I need to do the physics. Suppose you have a simple object... say, a beam of dimensions w, h, and d. Then suppose (for example) you apply a constant force at the...

once again I have succeeded in confusing myself about basic angular motion...:confused: If I have a pulley of with an unkown moment of inertia, and a bucket hanging from the pulley with a known mass, height, and acceleration in which it falls. Why can't i use: Torque = Ia rf = Ia r * mg...

Could someone direct me to a site that explains how the common moments of inertia were arrived at? My physics professor put up on the board today that for a uniform sphere: I=\frac{2}{5}mr^{2}. He said it was just the anti-derivative of something, but he didn't want to go into it because...

Part of my lab involves using the method of moments to calculate the weight of a meter stick. We attached two weights to different ends of the meter stick and are expected to calculate the weight of the meter stick based on the positions of the weights. I have no clue what the moment of methods...

using "primitives" to integrate moments of Inertia My classmates are lost and I just can't think the way my proffessor does when approaching these problems. He gave us about 50 shapes to find moments of inertia for this weekend and I'm not having any trouble doing them... my way. I can use a...

ok, X_1,X_2,...,X_n are independant(and unbiased) rectangular distributed random variables over the interval [0,a] It is known that T(X)=max(X_1,X_2,...,X_n) is sufficient. i am supposed to find the moment estimator for a using the method of moments. i know I'm supposed to equate the first...

Check my Moments... Edit: Deleting post because I think quite a bit of my work was incorrect--will repost tomorrow, corrected, hopefully...

mass of e is 100 kg mass of bar is 20 kg and acts at midpoint sume of moments about point a due to weight of bar and forces on b by bc, bd, and be, are 0, determine tensions in bc and bd so i continued like this. The moment about point A from all those forces is 0. 0 = (Raf x Wab) + (Rab...

I have a mechanics question that I can't seem to figure out. I've spent quite a bit of time on it but don't have much of an answer. If anyone can help I would appreciate it. Round objects are rolling without slipping down an inclined plane of height H above the horizontal. The box is...

Hello, I have a question concerning the GMM equation specification. Say we partition each day in 7 intraday intervals. We want to estimate the 7 intraday interval moments for a variable Y observed in those 7 intervals over a period of T days meaning we have t = T*7 total observations for...

Hi i was wondering, if the sphere is divided into 5 spherical shells, each shell has a different density and each shell is of equal thickness My question is: Can I calculate the moments of inertia for each shell by subtracting the moment of inertia of the sphere inside it, from the entire...

I found the following question in a textbook: Two men are carrying a uniform ladder of length 12m and weight 250N. One man holds the ladder 2.0m from the front end and the other man is 1.0m from the back of the ladder. Calculate the upward contact forces that each man exerts on the...

Hi can someone please do part ii) of this moments question. Just can't get my head round it. Thnx! http://img150.echo.cx/img150/872/physicspaper0128xk.jpg http://img150.echo.cx/img150/1093/p...paper0130ot.jpg

I have a "friend" who is the most annoying thing on the planet. He's jewish and is about to have his bar mitzvah, so he's taking hebrew classes. He's always trying to show off his hebrew reading abilities and I can't get him to shut up! Today we had an argument(after MIH's thread) about...

I'm having a lot of difficulty calculating the monopole and dipole moments for a dielectric sphere with surface charge of the form, sigma(theta)=sigma(0)cos(theta) If surface charge wasn't present and it was just a point charge I would be OK but I need a few pointers on how to do it with...

I'm stuck! This is the question: A uniform rod AB has length 3m and weight 120N. The rod rests in equilibrium in a horizontal position, smoothly supported at points C and D, where AC=0.5m and AD=2m. A particle of weight W Newtons is attached tto the rod at a point E where AE=x metres. The rod...

maybe I'm missing some stupid algebraic mistake..but given theta/theta + 1 = y. how does this imply that the method of moment is theta = y/ 1-y??