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Unformatted text preview: CHEM 356, Lecture 16, Fall 2009 1 Angular Momentum. Review of Classical Angular Momentum. u F 3 F 2 F 1 ℓ 2 ℓ 1 Illustration of the concept of scalar moments. Moment of a force: torque . ∙ The effect produced upon a body by a force of a given magnitude and direction depends upon the line of action of the force, specified by giving the perpendicular distance from a reference point to it. ∙ the concept is often employed to study the motion of a body that is free to rotate about some axis ∙ the perpendicular distance from the reference point to the line–of–action of a force is called the force–arm or moment–arm of the force about the axis. ∙ the product of the magnitude of force and its force–arm is called the moment of the force or torque about that axis. ∙ scalar moment : illustrate by examples. i) a positive translation F 1 gives rise to a counterclockwise moment, defined to be positive: 1 = + 1 1 . ii) positive translation F 2 gives rise to a clockwise (negative) moment: 2 = − 2 2 . iii) (negative) translation F 3 gives rise to zero moment: 3 = 3 ⋅ 0 = 0. CHEM 356, Lecture 16, Fall 2009 2 1. Overall scalar moment: if we have an arbitrary force vector F applied at a position whose location is given by the vector r , the overall scalar moment that it produces from action about an axis located at the origin for r is given by the sum of the moments...
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 Fall '09
 Prof.Iaskjd
 Angular Momentum, Force, Fundamental physics concepts, sin ???? cos

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