BASIC CONCEPTS

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BASIC CONCEPTS

• Force m a
• magnitude
• direction
• point of application
• Pressure Force/Area
• Torque (moment) r x F
• (Ref Williams Lissner Biomechanics of Human
  Motion LeVeau - Saunders)

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STATIC EQUILIBRIUM

• Useful state for analyses
• Body isolated in a free-body diagram
• Net forces on the body are zero
• (translational equilibrium)
• Net moments on the body are zero
• (rotational equilibrium)

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Ex. 1.1 Upper Limb with Weight
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LEVER SYSTEMS

• Forces acting around fulcrum (pivot point)
• External (resistive) forces are counter-balanced
  by internal muscle (effort) forces
• Forces act on moment or lever arms
• Ratio of forces (or lever arms) forms
• mechanical advantage re/rr Fr/Fe
• Three types 1st, 2nd, 3rd class

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1st CLASS LEVER(Fulcrum between effort and
resistance)
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2nd CLASS LEVER(Resistance between effort and
fulcrum)
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2nd CLASS LEVER(Resistance between effort and
fulcrum)
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3rd CLASS LEVER(Effort between resistance and
fulcrum)
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ANTHROPOMETRY

• Science of body size and characteristics
• Link lengths anthropometer
• Segment weights scales,
• water displacement mass vol x density
• Center of mass (center of gravity) suspension
  of cadaver parts
• biomechanics using moments
• moment of whole S moments of components

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FRICTION
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PULLEY SYSTEMS
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CRUDE PULLEY WITH FRICTION