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Torque. Angular analogue of force Rotary motion T = F x r r is the moment arm or perpendicular distance from the axis of rotation. Torque & Forces. Centric force External force directed through the COG Linear motion or translation Eccentric force
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Torque • Angular analogue of force • Rotary motion • T = F x r • r is the moment arm or perpendicular distance from the axis of rotation
Torque & Forces • Centric force • External force directed through the COG • Linear motion or translation • Eccentric force • External force not directed through the COG • Angular and/or linear motion or translation • Force couple • Combination of external forces causing solely angular motion
Examples of Torque • Figure 5.1 • Effects on torque • Moment arm length • Force application • Ease of applying force • Leverage/friction • Stability of axis of rotation • Friction (flat tire on wheel barrow) • Self-Experiments 5.1 to 5.6
Levers • First class • Second class • Third class
Application • Come up with five different examples of each type of lever mechanism! • Split up in to groups of two!
Muscular Torque • Figure 5.6 • Effectiveness of force application and leverage • Figure 5.5 + 5.8 • Moment arm length
Applied examples • Stability & Potential Energy • 3 point stance • 4 point stance • Defensive back lined up against a WR • Wrestler or MMA fighter
Stability & Balance • Stability • Linear • Resistance to disruption of equilibrium • Rotary • Resistance to disruption related to rotational equilibrium • Balance or Equilibrium • Ability to control equilibrium • Coordination and control • Base of support • Figure 5.17 • Major effects on stability
Center of Gravity • Point around which the mass and weight of an object are balanced in all directions! • Center of mass • Mass Centroid (Watch out the aliens are coming!) • COG for Objects • Figures 5.19, 5.20, & 5.21 • Borelli’s Reaction Board • Balance scale • Intersection of the 3 cardinal planes forms the COG
Equations of Equilibrium • Static equilibrium • Motionless state • Sum of all vertical, horizontal, and torques equals 0! • Dynamic equilibrium • D’Alembert’s principle • Bodies in motion have a balance between inertia effects and all vertical, horizontal, and torque components! • Elevator example • Elevator going up (greater mass of individual on scale)
Rotary Stability Factors • Increase the base of support • Line of gravity within base of support • Lower the center of gravity • Increase body mass • Extend base of support in direction of oncoming force • Move line of gravity toward an oncoming force
Rotary Stability Factors Combined • Adding the factors together increase stability! • Leaning, widening, squatting, crouching, etc. • Spinning enhances stability in certain objects! • Ice skater, spiral football pass, discus, etc. • Minimal stability positions • Track start with leverage (starting block) • Running race on ice • Which start is more stable? • Traditional or upright stance