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23 Cards in this Set
- Front
- Back
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Force |
interaction of an object with its surroundings - a vector quanitity - F= ma |
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Center of Mass |
a balance point about which all particles of mass are evenly distributed - located anterior to S2 level - will move as the body moves |
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Center of Gravity |
point of balance w.r.t. gravity |
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Anthropometrics |
studies the physical measurements of the body - allows estimates for COM, inertia, and Body segment weights relative to total body weight. |
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Joint reaction forces |
internal contact forces acting across a joint - bone on bone or ligament - axial (compression/distraction, perpendicular to joint surface) - shear (parallel to joint surface) |
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Ground reaction force |
Reaction force provided by a supporting surface |
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Friction |
force that arises when one body moves or tends to move across the surface of another, contact force. - always opposes motion -parallel to contact force - increase grip or impedes motion - independent of surface contact |
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Inertia |
resistance to change in state of rest or motion |
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Torque |
Force x moment arm (perpendicular distance from the line of action of an applied force to the axis of rotation) |
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Law of intertia |
a body continues in a state of rest or uniform motion except when it is compelled by external forces to change its shape |
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Law of Action/Reaction |
For every action there is an equal and opposite reaction
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Statics |
Branch of biomechanics dealing with rigid bodies at rest OR moving in uniform velocity
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Dynamics |
Branch of mechanics studying non-uniform motion |
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Osteokinematics |
bone motion relative to the cardinal plane |
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Arthrokinematics |
motion between articular surfaces of joints - improves joint fit -increases surface area -dissipates contact forces -guide bone motions |
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Purpose of Levers |
convert force to torque increase the mechanical advantage increase distance speed of movement |
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First class lever |
Effort and Resistance forces acting in same direction. Effort, Fulcrum, Resistance ex= skull and atlas vertebrae of spine |
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Second class lever |
Both forces on the same side of fulcrum. Fulcrum, Resistance, Effort |
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Third Class lever |
Both forces on same side of fulcrum Fulcrum, Effort, Resistance Most common in human body. Ex= bicep curl |
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Free Body Diagram |
simplified diagram of rigid body -represents all interactions influencing the system and its environment |
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Force Couple |
A set of forces that act about the same axis -different sides of fulcrum - equal in magnitude, opposite in direction. - translatory effects of either force are cancelled and the net result is Rotation. |
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Translation |
Caused by a force whose line of action passes through the COM or axis of rotation |
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Rotation & Translation |
a force whose line of action does NOT pass through the COM |
