Moment Definition and 85 Discussions

In mathematics, the moments of a function are quantitative measures related to the shape of the function's graph. If the function represents mass, then the first moment is the center of the mass, and the second moment is the rotational inertia. If the function is a probability distribution, then the first moment is the expected value, the second central moment is the variance, the third standardized moment is the skewness, and the fourth standardized moment is the kurtosis. The mathematical concept is closely related to the concept of moment in physics.
For a distribution of mass or probability on a bounded interval, the collection of all the moments (of all orders, from 0 to ∞) uniquely determines the distribution (Hausdorff moment problem). The same is not true on unbounded intervals (Hamburger moment problem).
In the mid-nineteenth century, Pafnuty Chebyshev became the first person to think systematically in terms of the moments of random variables.

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  1. N

    Convert moment force at lever support

    I am trying to determine if a clamp holding a lever with a mass at one end can experience zero or reduced torque either by balancing the forces or converting the rotational torque into another form such as linear, I’ve looked at counterbalance with Steadicams etc. but I believe this just...
  2. Tapias5000

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    I tried to solve it and I got the following is it correct? and 2 My solution... is a negative distance?
  3. MaratZakirov

    Rail Car with a Sail in the Wind

    I solve the following problem, there is a particle of mass ## m_p ## and velocity ## \vec{v}_p ## which collide with sail installed on rail car with mass ## m_c ## resting in the frame of reference associated with it before the collision. The cart is fixed on straight rails for which the vector...
  4. Camailee

    Engineering Statics problem: A ramp is supported by two cables

    Problem illustration: The possible answers are: I don't understand why it says Mc if it is asking for the moment at A, not C. But maybe I am getting something wrong. So with the formulas I posted above, I have this:
  5. goodOrBad

    Beam with a rope - type of problem (Statics)

  6. Jason234578

    Engineering Moment of a force about point O

    G'day. I have a problem with my statics work, i understand its probably quite simple but I am having trouble in my understanding. Essentially problems make more sense to me by using the component method, although in saying that i understand this problem would be quite a lot more simple were i to...
  7. M

    Engineering Moment and equilibrium

    Summary:: I need some help with moment when using equations of equilibrium Edit: Sorry I forgot to say what the question was! The question was to solve the value of R based on the diagram below alone. I was solving the question below and I tried to resolve R into a force that is perpendicular...
  8. Tymofei

    Calculating the Moment from a Different Vantage Point

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  9. D

    Engineering Moment vs simple connection

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  10. R

    Determining moment (or torque) around a certain point on a wrench

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  11. K

    Engineering Fluid Mechanics Problem: Water Forces on a Parabolic Gate

  12. A

    Torque: find the force necessary for a body to be in equilibrium

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  13. H

    Luffing Jib Load, With and Without Sheave Pulley

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  14. H

    Problem With a Slewing Bearing Crane

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  15. A

    Moment of a Force About a Point

    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...
  16. bardia sepehrnia

    Statics problem (moment and equilibrium)

    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...
  17. F

    Moment question

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  18. some4544

    I Force required to tip an object

    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...
  19. A

    Off-Axis Torque To A Cantilever Beam

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  20. B

    Dipole problem with electric fields

    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...
  21. T

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  22. Physicsterian

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  23. Andres Padilla

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  24. thee qs

    Magnetic moment and magnetic field and dot product

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  25. Muhammad Danish

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  26. Muhammad Danish

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  27. D

    Calculate the course of the Force and Moment

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  28. W

    I Spin confusion: Stern-Gerlach experiment

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  29. yavorh

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  30. S

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  31. marsupial

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  32. S

    Can we say Angular Velocity is a 'moment' of tangential velocity?

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    • Soumitra
    • Thread
    • angular frequency kinematics moment tangential velocity velocity
    • Replies: 7
    • Forum: Mechanics
  33. A

    Help with this moments problem

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  34. A

    Alternative approach -- Bicycle on a curve

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  35. B

    Moment Equilibrium in terms of box weight

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  36. S

    Rotational Motion Question, lever arm with two masses

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  37. O

    I Calculate the Dipole Moment of an object

    How would I calculate the Dipole Moment of a piece of mild steel approximately 15cm in length?
  38. Z

    Why don't we include the kinetic moments in the summation of the moments of a rigid body?

    Why don't we include the kinetic moments in the summation of the moments of a rigid body? In other words, why are the kinetic moments on the opposite side of the equation as the moments due to external forces? I understand that the math works out but it's not making sense to me conceptually...
  39. D

    Offset Torque Concept

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  40. R

    Finding the Moment of Inertia for a Rectangular Sheet

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  41. D

    How to determine direction of a moment

    Homework Statement I am following the first problem on this online pdf: http://www.ce.udel.edu/courses/CIEG212/Homework_1_2007.pdf Homework Equations Equilibrium equations for forces and moments. The Attempt at a Solution I know how to solve the problem, that part is straight forward. However...
  42. doktorwho

    Find the position of equlibrium

    Homework Statement From the diagram below find the position of the man (##x##) if the system is in balance. Total length is ##L## and the man is distance ##x## from one end. Homework Equations 3. The Attempt at a Solution [/B] I know that the system must be in balance if all the torque and all...
  43. doktorwho

    Help understanding torques and moments

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  44. W

    Statics -- Net Moment

    Homework Statement Homework Equations I can see how the net force is not the same but I'm not getting the net moment. The Attempt at a Solution 12mm x 10N = 120N-mm. How do these two FBDs not have the same net moments. Thanks for any help!
  45. J000e

    Maximum moment question

    Hey guys, I've been reading my strength of materials textbook and its pretty much like a reviewer that contain several problems and short descriptions of their concepts. There's this formula that computes the maximum moment for two moving loads and its: [PL-(Psmall)(d)]^2/4PL where P= Psmall...
  46. M

    Parallel Axis Theorem- Composite Areas (STATICS)

    Homework Statement Consider the beam shown in (Figure 1) . Suppose that a = 15 in. , b = 8 in. , c = 1 in., and d = 4 in. Determine the moment of inertia for the beam's cross-sectional area about the x axis...
  47. kamhogo

    What is the force exerted by each hinge on the door?

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  48. deusy

    Acceleration of the end of a hinged rod in a pulley system

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  49. T

    Early Statics Question

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  50. Alex Katko

    What variables are needed to find a moment?

    Homework Statement You wish to find the moment at the origin produced by a force, ̅F= {Fi}̂, that is applied at r= {̂ai+bj +ck ̂}. Which variables (F,a ,b,c , ) do we need to know to find a numerical answer? Explain using math and figures. Homework Equations Mo = r x F The Attempt at a...
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