Kinetics Flashcards

1
Q

kinematics

A

displacement of a segment without regard to forces

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2
Q

Kinematic variables

A

-type
-location
-direction
-magnitude
-rate

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3
Q

Displacement Types

A

Translatory: linear movement (isolated force through COM), straight line, anterior drawer test

Rotary: angular movement (2 equal and opposite forces not through COM), center of rotation COR

General movement: translation + rotation (isolated force not through COM), curvilinear motion 2D, 3D

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4
Q

Movement Types (axis, plane, direction)

A

Flexion/Extension: Saggital plane, x-axis

Rotation: transverse plane, y-axis

Adduction/Abduction: frontal plane, z-axis

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5
Q

Force

A

-push or pull exert on on and object
-F=ma (N or lbs)
-must be touching

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6
Q

Gravity

A

-constant
g=9.8 m/sec^2
w=mg
-most consistent and influential force encountered by the body in posture and movement

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7
Q

Static Equilibrium

A

-object remains at rest

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8
Q

Dynamic Equilibrium

A

-object moves at a constant velocity
-constant acceleration= no equilibrium

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9
Q

Newton’s 1st law

A

-Law of Inertia: object in motion stays in motion until another force acts on it
-if net forces don’t = 0, movement must occur
-if only 1 force, cannot be equillibruim

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10
Q

Newton’s 2nd Law

A

-Law of acceleration: acceleration is directly proportional to unbalanced forces or torques and inversely related to mass or moment of inertia

-F=ma
-Linear a=F/m
-Angular a= torque/moment of I

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11
Q

Moment of Inertia

A

I=m(r^2)
-r=distance from axis of rotation
-dependent on mass and distribution of the mass

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12
Q

Linear force systems

A

-2 forces act on the same line
-sum of forces

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13
Q

Concurrent force systems

A

-2 forces act on different angles
-solve for parallelogram trig

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14
Q

Newton’s 3rd Law

A

-Law of reaction: equal and opposite reaction
-reaction forces

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15
Q

Tensile forces

A

-lengthening
-opposite pulls on the same object
-parallel to long axis of segment

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16
Q

Joint distraction forces

A

-directed away front the joint surface
-perpendicular to joint surface

17
Q

Joint reaction forces

A

-when 2 segments are pushed together to touch
-compression force perpendicular to joint

18
Q

Shear force

A

-action is parallel to contacting surface
-movement between surfaces
-same direction of movement

19
Q

Friction force

A

-action is parallel to contacting surface
-opposite direction of movement
-static force is highest right before movement

20
Q

Force Couple

A

-2 forces in equal magnitude in opposite directions
-always produce torque

21
Q

Torque

A

T=(force)(movement arm)
-greater the force or distance between forces= greater torque

22
Q

Movement Arm

A

-shortest perpendicular distance b/w forces
-from axis of rotation to force

Perpendicular force= Larger MA
Parallel force (most muscles)= smaller MA

23
Q

Bending Moment

A

-3rd force applied to a force couple
-rotary equilibrium

24
Q

Torsional Moment

A

-rotation along long axis
-twisting

25
Anatomical Pulleys
-change in direction of the pull of muscle by bony prominence -makes task easier, increase movement arm= greater torque
26
Levers
-rigid segment that rotates around a fulcrum -Effort force (EF) great that Resistance Force (RF) to produce rotation
27
1st Class Lever
-axis of rotation (fulcrum) between EF and RF -scissors -tilting head back and forth OA joint= fulcrum Trap=effort Front of head= resistance
28
2nd Class Lever
-RF b/w fulcrum and EF -wheel barrel -Lifting heel off ground Toes on ground= fulcrum Calcaneus= resistance Gastroc= effort
29
3rd Class Lever
-EF b/w fulcrum and RF -shovel -Flexing elbow Elbow= fulcrum Bicep attachment= effort Wrist= resistance
30
Mechanical Advantage
-efficiency of the lever is determined by lengths of the lever arms -MAd=EA (MA of effort force)/RA (MA of resistance force) -EA>RA= MAd>1, requires less effort to move the lever
31
Force Resolution
Perpendicular: Fy, rotary Parallel: Fx, translatory -Pythagorean theorem
32
Angle of Application
-most angle of application muscles is small -parallel component of a muscle force is usually larger than the perpendicular component