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92 Cards in this Set
- Front
- Back
Biomechanics
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Application of mechanical principles to human and animal bodies in movement and in rest
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Kinematics
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description of motion without regard to the forces
time, acceleration, displacement, velocity, position |
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kinetics
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describing moving bodies and the forces that produce motion
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statics
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study of forces acting on a body in equilibrium
no acceleration-at rest, moving with a constant velocity, F=ma |
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Dynamics
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Study of forces acting on a body not in equilibrium
acceleration unbalanced forces |
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Arthrology
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study of joints of the body
articulation osteokinematics arthrokinematics |
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Arthrology-Articulation
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arthrology-articulation
joint union of adjacent bones, whether they enjoy movement or not |
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Arthrology
Osteokinematics |
osteokinematics
direction of movement of the distal segment of the joint |
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arthrology
Arthrokinematics |
arthrokinematics-
Direction of movement of articular joint surfaces -roll -spin -slide |
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Anatomic body position
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stand erect with feet together
look forward arms held at side elbows extended forearms supinated wrist and fingers extended |
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Planes-Frontal
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Frontal
aka-coronal or lateral Divides body into anterior (ventral) and posterior (dorsal) parts |
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Axis-Anteroposterior Axis
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Sagital
perpendicular to frontal plane horizontal front to back |
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Sagital Plane
coronal axis |
sagital plane- anteroposterior or median
divides body into right and left parts Coronal-horizontal or lateral perpendicular to sagital plane horizontal side to side |
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Transverse Plane
Longitudinal Axis |
Transverse Plane-horzontal
divides body into superior (cranial) and inferior(caudal) parts Longitudinal Axis- vertical perpendicular to transverse plane perpendicular to ground |
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Describing Anatomical Motion-Rule of Three
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Rule of three-
1.segment, moving on a 2.segment, moving on a 3.joint eg. (action)- tibia flexing on the femur at the knee Position- Tibia flexed on the femur at the knee |
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Measurements
English metric english gravitational SI |
English-foot,pound mass, second, poundal
Metric gravitational- meter, metric slug, second, kilogram force English Gravitational-foot, slug, second, pound force International system of units:SI Meter, kilo, second, kelvin, radian |
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Kinematics- Geometry of Motion
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Geometry of Motion
whole body motion component lever motion |
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Kinematics-Translatory Motion
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Translatory Motion- linear displacement
velocity acceleration |
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Kinematics- Rotary motion
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Rotary Motion
angular displacement angular velocity angular acceleration |
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Kinematics- Linear Displacement
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Linear Displacement-
Vector quantity -magnitude -direction ---positive or negative -meters, inches, etc. Differs from distance -distance is magnitude without direction d=x(over time)- x(initial) ?? |
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Kinematics- Linear Velocity
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linear velocity
-rate of displacement -vector quantity ---magnitude ---direction(positive or negative) Differs from speed -speed is a function of distance As time approaches zero, velocity approaches instantaneous velocity |
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Kinematics- Linear Acceleration
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Linear Acceleration
Rate of change in velocity (positive or negative-not deceleration) can be... zero, constant, changing Average acceleration- a=change in velocity divided by time |
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Kinematics-Angular Displacement
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Angular Displacement
-magnitude of rotation measured in...radians, degrees, revolutions Theta look on slide (page 3) (biomechanics) |
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Kinematics-Angular Velocity
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Angular velocity
rate of change of angular displacement as time approaches zero, w approaches instantaneous velocity Average angular velocity omega w=displacement divided by time |
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Kinematics-Angular Acceleration
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Angular Acceleration
rate of change in angular velocity (positive or negative, not deceleration) can be... zero, constant, changing Average acceleration Alpha=change in velocity divided by time |
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Kinematics- motion (def)
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motion- continuous change in position with respect to some reference point
object has been displaced |
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Types of Motion
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Types of Motion
translatory (linear) -rectilinear -curvilinear (some consider this general motion) Angular General |
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Translatory motion-rectilinear
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rectilinear- movement of an object or segment in a straight line
-all points move in parallel lines -all points move at an equal velocity |
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types of motion-translatory motion- curvilinear
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curvilinear-translatory motion along a curved path
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types of motion-Angular motion
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angular motion- movement of an object around a fixed axis
all points move at an equal angular velocity all points move at a unique linear velocity |
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types of motion- general ******* motion
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combination of translatory and angular motion.
rotation around a moving axis |
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Measurement of motion (systems)
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coordinate and collection
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Measurement of motion (coordinate system)
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Coordinate system- descriptive terms
clinical reference frames cartesian |
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Coordinate system-clinical
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clinical coordinate system
movement described in anatomic terms -elbow flexion -knee extension -thoracolumbar rotation |
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Coordinate system-reference frames
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reference frames-
movement described in relation to an anotomic landmark or an external landmark -left rotation of L4 on L5 -gait -flexion of the forearm on the humerous at the elbow |
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Coordinate system (motion measurement)
Cartesian |
coordinate system-
Cartesian x,y, and z planes and axes transverse plane hip rotation sagital plane knee flexion |
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Collection system (measurement of motion)
Direct |
Direct-
goniomentry --reliable --valid --high utility electrogoniometry --more reliable --more valid --lower utility accelerometry --measures acceleration of segment digital camera systems |
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measurement of motion- Collection system
Indirect |
Indirect
photography --stop action --measure off photo Video Recorders --multiple trials --measure off video |
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Goniometry
intratester vs. intertester validity |
Gonia=angle
Metron=measure Used to measure: total joint motion-range of motion Particular joint angle -joint position intratester-same joint by same tester intertester-same joint by different testers validity-does the obtained measurement equal the actual angle |
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Kinetics-Force
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Force-Mass times acceleration
push or pull produces, or tends to produce, a change in the state of rest or motion of an object A vector quantity -units --si: newton (Kg-m/sec squared) US: pound |
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Types of Forces: (4)
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Contact: force exerted by one object in direct contact with another
non-contact- force exerted by one object, without direct contact, on another object external: forces arising from outside the body internal: forces arising from within the body |
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vectors
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need: point of application, action line, magnitude, direction
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Force systems:
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linear, concurrent, parallel, general
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Force systems:Linear
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Linear force system
forces acting on the same object in the same line |
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Force systems: concurrent
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Concurrent:
forces acting on the same point but at different angles three forces are necessary for equilibrium |
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Force system:Parallel
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Parallel: forces acting on the same object but at different points
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Force systems: General
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General- forces acting on the same object across three planes
four forces required for equilibrium |
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Diagramming forces: two specific ways
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Diagramming Forces:
Free Body Diagram: Forces are drawn to correct proportion Space Diagram: Forces are located, but are not drawn to scale |
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Force Couples
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Two parallel forces equal in magnitude and opposite in direction
results in rotary motion-pure rotation (can have more than 2 forces contributing) |
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Composition
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Composition: Combining tow or more forces action in the same plane on the same point
a single resultant force eg. rotator cuff-combining effects of multiple forces |
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Resolution
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Replacing a single force by two or more equivalent force components
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Graphic Composition
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linear system
two or more vectors (add and subtract them) Concurrent system; two vectors, triangle method, parallelogram method, polygon method (3+ vectors) |
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Graphic Resolution
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linear system (2+ vectors)
concurrent systems (2 vectors) 3+ vectors Algebraic Resolution-find x and y component forces |
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Algebraic resolution and composition
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look in slides p. 18 and 19-21
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Angle of Pull (insertion)
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angle of pull (insertion) changes in the angle of pull (insertion) will vary the magnitude of the component forces.
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Friction
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Friction
force that resists motion -only exists when motion is attempted -- |
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-vector force (friction)
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line of action is always parallel to the contacting surfaces
Direction is opposite the direction of potential motion whenever two objects touch |
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Static friction
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friction force when objects are at rest
static friction must be overcome in order to initiate motion determined by magnitude of external load |
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Kinetic friction
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kinetic friction- friction force when objects are in motion
kinetic friction must be overcome in order to maintain motion remains constant while motion is occuring |
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Friction- refer to slides p. 22-24; 25-27
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22-24
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Friction- Clinical Applications
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angle of placement of crutches changes normal force, frictional force, and sliding force
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Newton's Laws
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1st-(law of inertia)- object will remain at rest or in uniform motion unless acted on by an unbalanced force
inertia is the property of an object that makes the object resist both the initiation of movement or a change in motion Second- (law of acceleration)- acceleration of an object is proportional to the force acting upon it and inversely proportional to the mass. F=ma A=F/m Acceleration may be a change in velocity or a change in direction 3rd- (Law of Reaction)- in order to achieve equilibrium -for every force (action), there is an equal and opposite reaction force |
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Levers
Simple Machine Classifications |
Simple Machine- two forces
--effort: causes the motion --resistance: resists the motion fulcrum Classifications: 1st, 2nd, 3rd. |
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First Class Lever
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2 forces on either side of fulcrum
>,< or = 1 1st class levers- favor either linear displacement and velocity of resistance or force |
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Second Class Lever- definition and mechanical advantage
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Resistance force is between effort force and fulcrum
Mechanical advantage- always>1 most mechanically advantageous and efficient --second class levers-favor less effort force, less linear displacement and velocity of resistance |
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3rd Class Lever-definition and mechanical advantage
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Effort force is between resistance force and fulcrum
mechanical advantage-Always < 1 always mechanically inefficient, effort arm always shorter than resistance arm most of our joints are 3rd class levers since it is more advantageous to have movement over force. 3rd Class levers- favor linear displacement and velocity of resistance, requires greater force |
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Mechanical Advantage
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Ratio of Effort arm length to resistance arm length
measure of efficiency effort arm/ resistance arm (always a measure of distance) |
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Angular vs. linear displacement and velocity
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angular displacement and velocity is the same for all points on the lever
linear displacement and velocity increases further from the axis reference slide p. 32 |
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Anatomic levers
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Anatomic levers- bones and joints constitute anatomic levers
-most 3rd class levers -anatomic trade offs --second class levers-favor less effort force, less linear displacement and velocity of resistance 3rd Class levers- favor linear displacement and velocity of resistance, requires greater force 1st class levers- favor either linear displacement and velocity of resistance or force |
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Pulleys- fixed
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Fixed Pulleys- pulley remains stationary in space
changes the action line of a force vector does not change the magnitude of a force vector |
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pulleys- moveable
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moveable pulleys- move through space
for every moveable pulley divide resistance in 1/2 and you'll have the amount of effort needed. or- number of strands divides the wieght efficient for force inefficient or distance traction equipment |
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anatomic pulleys
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anatomic pulleys- changes the action line of the muscle force vector
increases torque by increasing moment arm. deflect action line away from axis increases torque by increasing the rotary component increases angle of insertion eg. changes angle of quadraceps- deflects quad tendon away from center of knee --> increases insertion of quad another example, acromion at shoulder |
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anatomic pulleys- affect on torque, moment arm, action line, rotary component, angle of insertion
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increases- torque (by increase in moment arm) --> increase rotary component
increases angle of insertion deflect action line away from axis |
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wheel and axle
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wheel and axle-
causes or prevents rotation second class lever-resistance is set, effort arm changes as diameter of wheel changes |
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Torque- moment
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torque moment- when a force is causing rotation about an axis
Torque= Force times its perpendicular distance resultant torque is sum of all torques action on the lever= counter clockwise vs. clockwise resultant torque determines the direction of rotation of the lever Forces acting through the axis cannot produce torque because distance =0! |
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Work
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Work= Force x Distance (joules)
Force overcoming a resistance and moving an object through a distance |
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Power
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Power= work (force x distance) divided by time (watts)
amnt of work performed over time |
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Equilibrium
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Equilibrium- sum of all forces = 0
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Equilibrium- Static
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Equilibrium-static
object is at rest --velocity=0 |
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equilibrium- dynamic
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Equilibrium- dynamic
object is moving with a constant velocity |
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Equilibrium- rotational
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Equilibrium- rotational
must consider torque/moment lever systems |
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Equilibrium- translational
linear and concurrent |
Equilibrium- translational
linear- add and subtract vectors concurrent- three or more forces can result in equilibrium two concurrent forces need a third force to achieve equilibrium |
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Center of Mass
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Center of Mass
Center of gravity --point where gravity acts --line of gravity in the gravity force vector action on the COG All parts of body or of the part are evenly distributed Not confined to the physical limits of the part/body |
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Center of Mass
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Center of Gravity in Humans
-intersection of all three planes generally anterior to the S-2 spinal segment Line of gravity in Humans- Vector from COG to earth |
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Center of Mass- segmental parts
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COG in Humans can be broken into specific parts of the body (limbs, bony segments)--> segmental parts
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Center of Mass--Relocation of COG
Altering of COG |
Relocation of COG in humans
-unchanged in rigid parts -changes with position changes in segmental parts ALTERING of COG human COG can shift with changes in -body weight distribution (fatness, pregnancy) -lower extremity amputee -carrying an external load |
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Center of Gravity Stability
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Line of gravity must pass through the base of support
-whole body -segments |
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COG- Stability- BASE OF SUPPORT
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COG- Stability- BASE OF SUPPORT
-Area formed under the object -Increasing size of base of support increases stability |
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COG- Instability- BASE OF SUPPORT
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COG- Instability- BASE OF SUPPORT
-Line of gravity is passing outside of Base of Support --movement toward the line of gravity --return to starting position ---fall to new position |
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Stability- Height of Center of Gravity
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As Center of Gravity height increases, stability decreases
As COG height decreases, stability increases |
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Stability- Base of Support Size
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Stability- Base of Support Size
Increasing size of BOS increases stability |
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Maximizing Stability
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Low COG over large BOS will result in maximum stability
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