Moments Definition and 626 Threads

Moments (stylized MOMents) is a Filipino celebrity talk show hosted by Gladys Reyes and aired on Net 25. It is a show for mothers and kids that feature the different bonding moments, child-rearing styles and the many facets of motherhood. It airs 7pm every Saturdays with replays on Mondays to Fridays at 10 A.M and Sundays at 11:30 AM / 12:30 PM.

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  1. R

    Moments of Inertia/Center of Mass

    Could someone help me get started on these two types of problems? (In terms of what equations to use/what the problems are asking for or mean) Moments of inertia -A rigid body consists of 2 point masses m1= 1kg at a position vector r1= (1,2,3) m and m2 = 2kg at a position vector r2- (0,1,0)...
  2. Z

    Expanding f(z) with Known Moments: m_k

    given the set of moments m_k obtained from the known measure w(x) \int _{-\infty}^{\infty}dx w(x) x^{k} = m_k now if we define the moment generating function f(z)= \sum_{k=0}^{\infty} m_{k}(-1)^{k}z^{k} , which have the integral representation f(z)= \int _{-\infty}^{\infty}...
  3. B

    What Are Invariant Moments in 2D Images?

    Hi there I'm thinking about using the rotation invarient moments by Hu/Flusser (http://en.wikipedia.org/wiki/Image_moment#Rotation_invariant_moments). I'm a physicist by trade, with exceptionally poor math..! I'm not comfortable with exactly what these invariants are. The wikipedia link...
  4. K

    Moments and products of inertia

    Homework Statement Hey all I have a physics problem that I need some help setting up the problem: A bar of length 2L rotates with angular velocity \omega, which points in the +y direction. The bar makes an angle \alpha with the y axis, with its centre corresponding to the origin. The bar...
  5. D

    Homework help on Moments of inertia of system

    Homework Statement Four masses are held in position at the corners of a rectangle by light rods.Find the moment of inertia of the system about the x axis.Find the moment of inertia of the system about the y axis.Find the moment of inertia of the system about an axis through O and...
  6. D

    Calculate The Moments about the Point A, [Guidance needed]

    Hi, I need some guidance regarding this exercise, Homework Statement Calculate The Moments about the Point A I attached the visual representation of the exercise, it has common A(PIN)---------B(ROLLER) element, then two forces going down( 5 Kips & 2 kips ), then the distances about...
  7. F

    Understanding Weight Distribution on Beams: The Role of Rigid Body Moments

    how are weights distributed on a beam
  8. S

    Example where higher moments are infinite

    Can someone give me an example where we have \mathbb{E}z=0 , \mathbb{E}z^2=1 (i.e. finite expectations) BUT, \mathbb{E}z^4= \infty ? Also, I cannot think of a case where: \mathbb{E}x=\infty where x>0 BUT, \mathbb{E}| \log x |< \infty Thanks in advance
  9. L

    Calculating moments of intertia

    1. Find the moment of inertia I_x of particle a with respect to the x-axis (that is, if the x-axis is the axis of rotation), the moment of inertia I_y of particle a with respect to the y axis, and the moment of inertia I_z of particle a with respect to the z axis (the axis that passes through...
  10. N

    Statics - Impending motion, moments help

    Homework Statement The cup shown in the picture is filled with 6 oz of coffee. The center of gravity is located at G. If a vertical force is applied to the rim of the cup a shown in the picture, determine its magnitude so that the cup is on the verge of tipping. Homework Equations sum...
  11. J

    Dermining moments caused in tension of cable

    Determine the moment created about the support leg at "A" caused by the tension in the cable of 12.3kN. (see attachment for diagram)
  12. G

    Statics Homework-couple moments- can't find where to start

    Homework Statement I am in my second year of mechanical engineering. This is a statics problem i would like help starting http://img230.imageshack.us/img230/9501/hw1z.jpg Homework Equations The Attempt at a Solution I know I need to calculate the force time distance but...
  13. B

    Exploring Higher Order Moments and Sample Size Infinity in Random Variables

    Hi, all, Let's assume a random variable's variance is zero as sample size tends to infinity somehow, can I say that its higher order central moments are also zero as the sample size tends to infinity? Thks a lot
  14. L

    To find the density of a material of the body using moments

    Homework Statement [PLAIN]"[URL=http://img193.imageshack.us/my.php?image=63378846.png[/URL] Fig.A shows the balanced position of a light rod carrying an object X and a mass M . Fig.B shows the balanced position of the same system when X is immersed in water.If the density of water is d,the...
  15. P

    Moments in QM: When Can I Say JLS^2 Approx Equal JL+S?

    \vec{J} - mechanical moment \vec{L} - orbital moment \vec{S} - spin moment \vec{J}=\vec{L}+\vec{S} When can I say J^2\approx J(J+1) L^2\approx L(L+1) S^2\approx S(S+1)?
  16. Z

    Moments - How to Calculate Tension in a Cable to Supply a Given Moment?

    Homework Statement "In raising the pole from the position show, the tension T in the cable must supply a moment about O of 72 Knm. Determine T." Homework Equations M = Fd The Attempt at a Solution d = 12sin(30) = 6m T = 72/d ==> 12m I do not know what I am doing wrong...
  17. Q

    Understanding Moments: Exploring Equilibrium and Line of Action

    Ok, so for equilibrium (no moment about any point), all the lines of action must pass through a single point right? But what about a plank, balanced at its centre, with forces on both sides of the plank so the forces are in equilibrium, and there is no moments also. But what about the line of...
  18. S

    Resultant thrust and overturning turnning moments

    Homework Statement A vertical sluice gate is 5 meters wide and 3 meters deep. calculate the resultant thrust and overturnning moment when the water is level with the top edge of the gate. Density water = 1000kg/m^3 Homework Equations Newton's First Law F = ma Moment = Force x...
  19. M

    Statistical moments and multipole moments

    Hello, in statistics, one can derive the moments of a distribution by using a generating function <x^n> = \int dx x^n f(x) = \left( \frac {d}{dt} \int dx \exp(tx) f(x) \right)_{t=0} = \left( \frac d {dt} M(t) \right)_{t=0} Is there a similar method to derive the multipole moments in...
  20. R

    What is the Gaussian Integral for Moments?

    Hi, I'm trying to use moments to find the mean of a pdf. Here is the pdf: f(x|\theta) = 2 \theta^{-2}x^3 exp(\frac{-x^2}{\theta}) I'm not really sure where to start. I can multiply the pdf by X and then integrate with respect to X, but it gives me the wrong answer. Any ideas...
  21. C

    Calculating Bending Moment and Shear Forces in a Beam | Helpful Tips

    Homework Statement Calculate the magnitude of the bending moment and shear forces at the centre of the beam shown in the attached figure Homework Equations The Attempt at a Solution For the shear forces I think its the sum of the vertical components, Bending moment = not...
  22. J

    Solving Truss Loads: Moment, Trusses & Reactions

    Homework Statement http://i277.photobucket.com/albums/kk63/sarcasticlil123/truss.jpg Homework Equations p1=800#, p2= 600# and a=8, determine a reaction load The Attempt at a Solution sum Ma=0=-4.5p1-6p2+12.5cy I am generally lost, this isn't homework its practice for the final...
  23. D

    Understanding How to Add Moments Together: Explained and Clarified

    Hi people, I'm a bit confused as to when we can and cannot add 2 moments together. From what I understand, we CAN add them together if they are both about the same origin but CANNOT if they are about different origins. But when drawing and calculating bending moment diagrams, you have to...
  24. B

    Moments Question: Bike Equilibrium Conditions

    Homework Statement A bicycle of a mass 15kg resting in a vertical position, with the front and back wheels touching the horizontal ground at points P and Q respectively, where PQ=1m. The centre of gravity of the bike is vertically above O, a point on PQ where PO=30cm. Given that the normal...
  25. K

    Finding Center of Mass for a Lamina in First Quadrant

    Homework Statement A lamina has the shape of the region in the first quadrant that is bounded by the graphs of y = sinx and y= cosx, between x = 0 and x = π/4. Find the centre of mass if the density is δ(x,y) = y. Homework Equations I know all the equations for moments and center of...
  26. M

    Rolling hemispheres and moments of inertia

    Homework Statement Hi there - I'm working through a bit of mechanics revision and have been looking at some of my uni past exam papers from a good few years back when the syllabus was different, so I'm not familiar with a lot of the material covered - it's not strictly relevant to my current...
  27. H

    Inertia Translation Rotation Moments And Couples, car on accelerating Treadmill

    I have been asked to come up with a formula by a rather persistent person who is Addiment that a wheel on an accelerating treadmill attached to a mass (such as a car) would not produce enough translational force to move the Car. The Question as posed to that persons; Please forgive any and...
  28. H

    Moments of Inertia of a Flat Body

    How do you take the moments of inertia of a flat body? I know howto take it if it's a 3d body. And the 2d case should be really simpe,but I'm too stupid to figure it out. Can you help me? For example.. Say we have a body that's a rectangle of mass m on |x| < a, |y| < b..? Thanks so much.
  29. P

    Completely not understanding moments help

    there are 2 questions which are driving me insane because I jus don't understand what to do! I hope that if someone could go through the questions in detail then I'll finally understand how to go about answering. 5. A rod AB of mass 6kg and length 3m has its centre of mass 1.2m from A. It is...
  30. M

    Calculating End Reactions: How to Sum Moments of All Forces About a Point

    Hi,I am trying to calculate the end reactions for the beam shown in the diagram attached. I have got this far but know I am going wrong somewhere. To check ,RA + RB should equal the total load,point and UDL so I am told. Can someone point me in the right direction please. Many...
  31. L

    Calculating Dipole Moment for Equilateral Triangle Distribution of Charges

    Homework Statement Find the value of the dipole moment of the distribution of charges. -2q on top of equilateral triangle +q on each of the other points. Each charge is separated by distance d. Homework Equations p = \sum (q_i)(r_i) The Attempt at a Solution p =...
  32. Z

    Statics: Solving Moments Homework Help

    Homework Statement I got a problem solving this question. http://img228.imageshack.us/img228/7049/image164.jpg The Attempt at a Solution Im not sure if I am missing a rule here. I take CW to be positive and CCW to be negative. But my attempt to solve it failed =[...
  33. A

    Find the principal moments of inertia of a flat rectangular plate

    Hello everyone; here is the problem that I’m currently working on: =============================================== a- Find the principal moments of inertia of a flat rectangular plate (mass = 30g, a = 80 mm, b = 60 mm) that rotates about a diagonal with velocity ω = 15 rad/s. b- What are...
  34. W

    Moments Of A Couple probably just something simple.

    Homework Statement http://i124.photobucket.com/albums/p27/lollipopgourmet/untitled.jpg If the couple has a magnitude of M, determine the magnitude F of the couple forces. Since this is an X-Y plane, I assumed the equation would simple just be M=Fd, where I know the moment, and just have...
  35. T

    How to Find Component Forces in Static Equilibrium with Moments?

    Homework Statement Find the component forces Az, Ay, Bx, By, Cx, Cz: http://phga.pearsoncmg.com/onekey/web/hibbelerSD10e/Public_Html/chapter05/H-4ed-5-92a-fbd.gif Homework Equations The downward force at the origin is 250 lb and the moment is 25 ft-lb The Attempt at a Solution Well first...
  36. J

    Moments - Principle of moments question

    I am trying to determine force X I know it is the principle of moments so I think you use this equarion - not sure though: In equilibrium (the sum of)anticlockwise moments = (the sum of) clockwise moments...
  37. M

    Why Do We Add Mc and Mf in Calculating Resultant Couples?

    Moments and force couples...confused! Homework Statement I have attached 2 pdfs: 1 is the problem, the second is the solution. I need help understanding the solution. Diagrams included. The gist of the problem: Need to calculate a dimension "a" such that a resultant couple (from 2 force...
  38. Q

    NMR, Nuclear & Electron magnetic moments

    I have got myself very confused. I am trying to understand Nuclear Magnetic Resonance but am running into issues. The basic idea of NMR, resonant excitations between Zeeman split nuclear energy states, I understand. The semi-classical picture of precessing moments also makes some sense to me...
  39. T

    How Do You Calculate Torque to Determine String Tension in Physics Problems?

    Homework Statement I am stuck on question 6c on this paper. Can anyone have a look at it please. I don't know were to start. do I place the rock 'x' meters away from one of the strings and set one of the strings tension to 40g? Homework Equations The Attempt at a Solution
  40. A

    Beam Bending and Moments of Inertia

    Homework Statement This is a two part question. In the first part you are asked to determine the mam moment that can be applied to the beam if it is bent about the z axis. They then ask you to redo the question bending about the y axis. This is probably a really simple question but what is the...
  41. T

    Help calculation torque, moments.

    Homework Statement A uniform rod AB of length 4m and mass 2kg is suspended in a horizontal position by two vertical strings attached at points p and Q where AP=1m and AQ=3m. When a particle of mass 3kg is attached at point R of the rod, the rod is on the point of turning about point P...
  42. B

    Calculating Reactions and Bending Moments for Fixed End Beam

    Homework Statement Fixed end beam with Length = 1m Load 1 = 58.86n @ 0.4m from A Load 2 = 39.24n @ 0.85m from A Find Ma, Mb, Ra, Rb Homework Equations Not Sure, where help is needed The Attempt at a Solution Well i think, almost sure from 2 methods that Ra = 40.52511...
  43. L

    Moments of Inertia, Kinetic Energy and rotations

    Homework Statement A bicycle racer is going downhill at 11.0 m/s when, to his horror, one of his 2.25 kg wheels comes off when he is 75.0 m above the foot of the hill. We can model the wheel as a thin-walled cylinder 85.0 cm in diameter and neglect the small mass of the spokes. How fast is...
  44. N

    Forces and Moments in Moving Frameworks

    I'm trying to create a simulation of some frameworks. For my situation, these are light (I'm ignoring their weight) rods connected by joints. Currently, the joints do not hinge or otherwise move and can have a weight, effectively a force applied to the point. Oh, and I'm also ignoring air...
  45. V

    How Do You Calculate the Dipole Moment of CO2 with a 120 Degree Bond Angle?

    Homework Statement r-bond length (in anströms) q-charge (in debyes) CO2 r(CO)=1.1867 q(C)=1.1352 q(O)=-0.5676 angle between them is 120 deg Homework Equations The Attempt at a Solution I know I have to make vectors and then add them, but I don't know how to make the vectors. I...
  46. E

    Physics Homework: Moments and Tension

    Homework Statement A flagpole of mass 25kg and 2.5m in length is held in a horizontal position by a cable shown in the diagram. The centre of gravity of the flagpole is at a distance of 1.5m from the fixed end. Determine: a the tension T in the cable; b the vertical component of the force...
  47. O

    Unlocking 3D Equilibrium and Moments

    3D Equilibrium(and Moments) Homework Statement Homework Equations Sum of the forces in x=0 Sum of the forces in y=0 Sum of the forces in z=0 Sum of Moments (at a point) =0 (of x,y,z) The Attempt at a Solution Since it is a fixed end there is 6 unknowns right at the origin (Ax, Ay, Az...
  48. Philosophaie

    Dipole Moments of the Planets and the sun

    I am wondering if there is a source of the magniude of the Dipole moments of all the planets and the sun, m. m(earth) is 8*10^22 A*m^2. The Magnetic Field and the Electric Field such that: Br = Mu0/4/pi*2*m*cos(Theta)/r^3 Btheta = Mu0/4/pi*m*sin(Theta)/r^3 Mphi = 0 Er =...
  49. V

    Help with some Moments problems

    Homework Statement The direction cosines of the force F are cos \varthetax= .818, cos\varthetay= .182, cos\varthetaz= -.545. The support of the beam at O will fail if the magnitude of the moment of F about O exceeds 100 kN-m. Determine the magnitude of the largest force F that can safely be...
  50. O

    How Do You Draw an Equivalent System for a Given Moment?

    Homework Statement Here is the problem I am stuck on, need some advice Homework Equations ----- The Attempt at a Solution I found the moment to be -19.282 for the system shown (not sure if it correct) but I am confused about how to drawing will look for the equivalent system. (- is added for...
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