# UMass Amherst KIN 296 - angular-kinetics-1 (1) (8 pages)

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## angular-kinetics-1 (1)

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## angular-kinetics-1 (1)

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Pages:
8
School:
University of Massachusetts Amherst
Course:
Kin 296 - Independent Study

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Angular Kinetics of Human Movement Ch 11 Torque Torques Moments and Levers Center of Mass Gravity Moment of Inertia Angular Analogues of Newton s Laws Angular Momentum and Impulse Angular Work and Power Equations of Motion Segmental Analysis Inverse Dynamics Torque Force Couple Two equal but oppositely directed forces F1 F2 0 separated by a distance will form a force couple d The force couple will produce a torque T F1 d causing rotation However there will be no translation because F1 and F2 will cancel each other out in terms of translation A net centric force will cause translation A net eccentric force will cause translation rotation Calculating Torque Torque Force perp distance perpendicular distance r Copyright 2017 Brian R Umberger Ph D University of Massachusetts Amherst Force F Axis or Center of Rotation Lever Torque is equal to force times perpendicular distance T F r Torque is also referred to as moment of force The perpendicular distance r from the axis of rotation to the force is known as the moment arm 1 Calculating Torque Calculating Torque Two ways to calculate torque created by a force Force F Axis or Center of Rotation Lever Often the force does not act perpendicular to the lever to which it is applied using moment arm r2 of the resultant force using moment arm r1 of the rotary component FMUS FMUS How do you calculate the torque in such cases r2 r1 Muscle Torque Tmus Fmus r Fmus FNR What is the perpendicular distance r in this case FR T F r r1 r2 r1 sin so FR FMUS sin so T FMUS r1 sin T FMUS sin r1 Muscle Torque The torque produced by a muscle is equal to muscle force Fmus times muscle moment arm r FMUS FR FMUS FR FMUS Tmus Fmus r FNR r Center of Joint Rotation The muscle moment arm is the perpendicular distance from the line of action of the muscle force to the center of rotation of the joint If muscle attaches to bone at an angle only the component of muscle force perpendicular to the bone FR rotary component contributes to the muscle torque 2

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