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Moment (physics)
 
 
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In physics
Physics

Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
, the term "moment" can refer to many different concepts:



where


is the vector from point A to the position where quantity B is applied. × represents the cross product
Cross product

In mathematics, the cross product is a binary operation on two vector s in a three-dimensional Euclidean space that results in another vector which is orthogonal to the plane containing the two input vectors....
 of the vectors.

Thus M can be referred to as "the moment M with respect to the axis that goes through the point A", or simply "the moment M around A".






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In physics
Physics

Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
, the term "moment" can refer to many different concepts:
  • Moment of force (often just moment) is a synonym for torque
    Torque

    Torque is the tendency of a force to rotate an object about an axis . Just as a force is a push or a pull, a torque can be thought of as a twist....
    , an important basic concept in physics, civil engineering, and mechanical engineering. In the context of mechanical engineering, the terms are not necessarily interchangeable, but one or the other may be preferred in a specific context. For example, "torque" is usually used to describe a rotational force down a shaft, for example a turning screw-driver, whereas "moment" is more often used to describe a bending force on a beam.
    • Moment arm is a quantity used when calculating torque. See the article torque
      Torque

      Torque is the tendency of a force to rotate an object about an axis . Just as a force is a push or a pull, a torque can be thought of as a twist....
      .
    • The Principle of moments is a theorem concerning torques. See the article torque
      Torque

      Torque is the tendency of a force to rotate an object about an axis . Just as a force is a push or a pull, a torque can be thought of as a twist....
      .
  • Moment of a vector is a generalization of the moment of force. The moment M of a vector B about the point A is




where


is the vector from point A to the position where quantity B is applied. × represents the cross product
Cross product

In mathematics, the cross product is a binary operation on two vector s in a three-dimensional Euclidean space that results in another vector which is orthogonal to the plane containing the two input vectors....
 of the vectors.

Thus M can be referred to as "the moment M with respect to the axis that goes through the point A", or simply "the moment M around A". If A is the origin
Origin (mathematics)

In mathematics, the origin of a Euclidean space is a special Point , usually denoted by the letter O, used as a fixed point of reference for the geometry of the surrounding space....
, or, informally, if the axis involved is clear from context, one often omits A and says simply moment.


When B is the force, the moment of force is the torque as defined above.


  • Moment of inertia
    Moment of inertia

    Moment of inertia, also called mass moment of inertia or the angular mass, is a measure of an object's resistance to changes in its rotation rate....
      is analogous to mass
    Mass

    In physical science, mass refers to the degree of acceleration a body acquires when subject to a force: bodies with greater mass are accelerated less by the same force....
     in discussions of rotational motion.
  • Angular momentum
    Angular momentum

    In physics, the angular momentum of a particle about an origin is a vector quantity related to rotation, equal to the mass of the particle multiplied by the cross product of the position vector of the particle with its velocity vector....
      is the rotational analog of momentum
    Momentum

    In classical mechanics, momentum is the product of the mass and velocity of an object . For more accurate measures of momentum, see the section Momentum#Modern definitions of momentum on this page....
    . (Historically, angular momentum was sometimes referred to as "moment of momentum".)
  • Magnetic moment
    Magnetic moment

    In physics, astronomy, chemistry, and electrical engineering, the term magnetic moment of a system usually refers to its magnetic dipole moment, and is a measure of the strength of the system's net Magnetism....
      is a dipole
    Dipole

    In physics, there are two kinds of dipoles :*An electric dipole is a separation of positive and negative charge. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some, usually small, distance....
     moment measuring the strength and direction of a magnetic source.


Simply put, The equation of the moment of the force. M=Fd

M= moment F=force d= distance from the pivot