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37 Cards in this Set
- Front
- Back
Biomechanics
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-Response of biological systems to mechanical forces
-Application of mechanical laws to living systems |
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Statics
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Equilibrium of bodies at rest or moving with a constant velocity
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Dynamics
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Bodies in motion, forces that act to produce motion
-Kinematics and Kinetics |
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Kinematics
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Geometry of motion w/o consideration of forces
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Kinetics
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Force analysis of bodies in motion
Relationship between forces acting on a system |
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Forces
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Mechanical Disturbance or Load
-Produce, halt or change direction of motion -Magnitude and Direction - Vectors -F=ma |
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Magnitude
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Amount of Force applied
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Orientation
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Angular position of the line
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Line of application
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angle with body that force is acting on
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Moment of Force
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Magnitude of force x perpendicular distance to the axis of rotation
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Torque
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Force x Perpendicular distance to center of rotation
Produces rotation |
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Moment Arm
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Shortest distance between axis of rotation and force
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Torque =
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Force x Moment Arm
-Rotary equivalent of force -Force produced by a muscle |
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Mass
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Amount of matter composing an object
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Weight
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Force acting on an object due to gravity
-Depends on mass of object and strength of gravitational pull |
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Center of Gravity
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-Rigid body behaves as if its entire mass were acting at its COG
-Point at which total mass of body is considered to be concentrated -Depends on body's shape and mass distribution -Point of Application of force due to gravity -Located normally around S2 |
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Line of Gravity
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Line extending from COG vertically downward
Vector representation of the weight of a segment |
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Base of Support
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Outline on ground encompassing all parts of the patient which touch the ground
-To be stable the COG must fall in the BOS |
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To incrase stability
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Increase BOS and Lower COG
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Friction
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Tangential force acting between two bodies in contact which opposes motion
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First Class Levers
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Fulcrum always located between Effort and Resistance
-C1 |
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Second Class Levers
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Effort Arm is always greater than Resistance Arm
-1st MTP Standing |
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Third Class Levers
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Resistance Arm is always greater than Effort Arm
-Biceps Curl |
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Mechanical Advantage
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-Efficiency of a lever
-Effectiveness of Effort compared to Resistance -EA/RA |
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Law of Inertia
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A body at rest remains at rest, and a body in motion remains in uniform linear motion, unless acted upon by an outside force
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Inertia
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Resistance to initiation or change of motion
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Law of Acceleration
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-Body acted on by a force will accelerate in direction of force in proportion to its mass
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Law of Reaction
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-For every action there is a reaction, equal in magnitude but opposite in direction
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Coplanar
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2 or more forces acting in the same plane
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Concurrent
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2 or more forces acting on the same point
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Collinear
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2 or more forces acting along the same line
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Parallel Forces
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Tensile Forces
-Normal force perpendicular and directed away from surface Compressive Forces -Normal forces perpendicular and directed towards the surface *Forces that are parallel, coplanar but have different point of application |
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Coplanar Forces
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Resultant force is algebraic sum of vectors
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Parallel Forces/Force Couples
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2 parallel forces equal in magnitude and opposite in direction, but not in same straight line
-Cause rotation of parts around thier anatomical axis |
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Concurrent Forces
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2 forces with same point of application but different direction of action lines
-Coplanar, concurrent, not collinear |
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Rectangular Components
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Muscle force applied to bone (via tendon)
-When muscles contract to produce movement, some force is used for rotation and some is used for compression |
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Translatory Component
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Portion of force applied parallel to lever
Pazss through joint axis, does not produce torque Tangential component of force |