kinematics Flashcards
(98 cards)
1
Q
what is kinematics?
A
displacement or motion of a segment without regard to forces that causes movement
2
Q
what are the five kinematic variables?
A
type
location
direction
magnitude
rate
3
Q
what type of displacement?
linear displacement
movement of segment in a straight line
A
translatory
4
Q
what type of displacement?
angular displacement
movement of segment around a fixed axis (COR)
A
rotary
5
Q
what type of displacement?
translation + rotation
A
general motion
6
Q
which type of displacement is rare in human movement?
A
translatory
7
Q
which type of displacement is a majority of human movement?
A
general motion
8
Q
what is an example of translatory displacement in physical therapy?
A
ACL test (knee moves forward with an ACL tear)
9
Q
what is an example of 2D general motion?
A
curvilinear motion (ICoR or IaR)
10
Q
what is an example of curvilinear motion?
A
joint motion
11
Q
what is an example of 3D general motion?
A
screw home mechanism
HaM
12
Q
what movements are in the coronal and sagittal plane?
A
flexion/extension
13
Q
what movements are in the vertical and transverse plane?
A
internal/external rotation
14
Q
what movements are in the anteroposterior and frontal plane?
A
abduction/adduction
15
Q
what is the unit of measurement for rotation and what is the max?
A
degrees; max is 360
16
Q
what is the unit measurement for translation?
A
inches, feet, meters, etc.
17
Q
what is magnitude and how do you measure it?
A
range of motion - goniometer
18
Q
what is speed?
A
displacement per unit of time, regardless of direction
19
Q
what is velocity?
A
displacement per unit of time in a given direction
20
Q
what is force?
A
a push or pull exerted by one object on another
21
Q
what are the two primary rules of forces?
A
- all forces on a segment must come from something that is contacting that segment
- anything that contacts a segment must create a force on that segment
22
Q
what are external forces?
A
pushes or pulls arising from outside the body
23
Q
what is a constant external force?
A
gravity
24
Q
what are internal forces?
A
forces that act on structures of the body and arise from within the body
25
what are examples of internal forces?
muscles
ligaments
bones
26
when masses of two or more segments are combined, the new COM vector is where?
between and in line with the original two COM vectors
27
if the segments are unequal in mass, where does the new COM vector lie?
closer to the heavier segment
28
what is the new vector called when two or more vectors are combined?
the resultant force
29
what does combining two or more forces into a single resultant force become?
composition of forces
30
in anatomical position, where is the COM typically found?
anterior to S2
31
in anatomical position, where is the BOS (base of support)?
lying between their feet
32
for an object to be stable, where does the line of gravity must fall?
within the BOS
33
what are two factors that can increase stability (hint: BOS and COM)?
wider BOS
lower COM
34
what is static equilibrium?
object remains at rest
35
what is dynamic equilibrium?
object moves at a constant velocity
if there is acceleration, there is no equilibrium
36
what does balanced forces result into?
equilibrium
37
what does unbalanced forces result into?
acceleration
38
what is the law of inertia (Newton's 1st law)?
an object will continue in current motion until a force causes the speed or direction to change
39
Newton's 1st law:
there can be multiple forces being applied to an object BUT when the sum of forces or torque do not equal 0, then the object must be _________.
accelerating
40
Newton's 1st law:
if there is only ONE force, there cannot be ________
equilibrium
41
what is the Newton's 2nd law of acceleration?
the moment of inertia is dependent upon the size of the object and the distribution of mass
42
in the Newton's 2nd law of acceleration:
acceleration of an object is _____ proportional to the unbalanced forces or torques and _____ proportional to the mass or moment of inertia
directly
inversely
43
summarize law of acceleration or Newton's 2nd law in simple terms.
a larger net force acting on an object causes a larger acceleration
objects with larger mass require more force to accelerate
44
what are linear force systems?
two or more forces work on the same segment in the same line
45
what is the resultant force in the linear force systems?
sum of the magnitudes
46
what are concurrent force systems?
two or more forces work on the same segment from different angles
47
what is the law of reaction (Newton's 3rd law)?
for every action, there is an opposite and equal reaction
48
law of reaction - Newton's 3rd law:
two objects touching each other result in _______ forces
reaction
49
true or false: reaction forces are never part of the same force system because the forces are acting on different objects
true
50
how are tensile forces created?
created by opposite pulls on the same segment/object
51
true or false:
tensile forces are perpendicular to the long axis of the segment/object
false --> parallel
52
where are joint distraction forces directed?
away from the joint surface to which its applied
53
joint distraction forces are (perpendicular or parallel?) to its joint surface
perpendicular
54
what do joint distraction forces lead to?
a separation of the joint surfaces
55
what are joint reaction forces?
when two body segments are pushed together and touch
56
joint reaction forces are (perpendicular or parallel?) and directed (away or toward?) the joint surface
perpendicular and toward
COMPRESSION FORCES
57
ankle weight on ankle in sitting is what type of force?
distraction force
58
ankle weight and foot up on leg press is what type of force?
compression force
59
what is shear force?
the action of the force is parallel to the contacting surfaces
allows movement between the surfaces
60
shear force is applied in the ________ direction as movement?
SAME
61
what is friction force?
the action is parallel to the contact surfaces
62
Friction is applied in the ______ direction of movement
OPPOSITE
63
when is the magnitude of friction at its greatest?
the magnitude of friction is always greatest JUST BEFORE the object moves; this results in a drop of friction once the object is moving
64
isolated force through COM
translation
65
isolated force NOT through COM
rotation and translation
66
two equal and opposite forces
rotation
67
what is force couple?
two forces equal in magnitude, opposite in direction, parallel and applied to the same object at different points
68
the greater the force or distance between forces the ______ the torque
greater
69
parallel force systems
when two or more forces applied to the same object are parallel to one another
70
parallel force systems:
how is the torque generated determined?
multiplying the magnitude of the force by its moment arm
71
parallel force systems:
how can resultant torques be determined?
adding torques
72
when a third force is added to a force couple resulting in rotary and translator equilibrium, what is it called?
bending moments
73
what is an example of bending moments?
bone fracture
74
what is a torsional moment?
rotation of a segment around its long axis (twisting moment)
75
what is an example of a torsional moment?
spiral fracture
76
what direction does any muscle pull toward?
the center of the muscle
77
when does movement occur for a muscle?
when the torque of a muscle exceeds opposing torques
78
the direction of pull of a muscle is deflected by what?
a bony prominence
79
what are the function of the anatomical pulleys?
change the direction of the force, without changing the magnitude
80
what does the pulleys do the moment arm and the torque?
increase the moment arm by deflection the action line further from the joint axis
the same amount of force will then produce greater torque
81
at 90 degree of knee flexion,
GAwLf MA is ________
where does the GAwLf vector passes through?
negligible
the joint axis
82
at 45 degree of knee flexion,
GAwLf MA _______
and what happens to torque?
increases,
more torque is required from the quad
83
at 0 degree of knee extension,
GAwLf MA ______
and what happens to torque?
increases 2x
the most amount of torque from the quad
84
which degree of knee flexion or extension requires the most amount of torque from the quad?
0 degree knee extension
85
at 0 degrees or knee extension,
GAwLf is _______ to its MA, resulting in an overall _________ force
perpendicular, increased
86
a force is applied perpendicular to the segment being acted on will have a ________ MA
larger
87
a force applied at 0 or 180 to the segment will have a _________ MA
smaller
88
true or false:
the angle of application and MA of a muscle force will vary with the angle of the joint it crosses as the segment moves
true
89
true or false:
Gravity's angle of application will change in relation to the position of the segment in space as well
true
90
the greater the moment arm, what happens to the pull of gravity?
it is greater
91
type of muscle contractions:
concentric
*give an example
active shortening
picking up a coffee cup
92
type of muscle contractions:
eccentric
*give an example
active lengthening
lowering a cup of coffee
93
type of muscle contraction:
isometric
*give an example
rotational equilibrium - while there is no movement, there is an active muscle contraction
keeping a coffee cup still between table and mouth
94
open chain
the distal end of the segment is free to move
95
closed chain
the distal end of the segment is fixed
96
angle of application:
T:F -->
the action line is parallel rather than perpendicular to the bony lever
true
97
angle of application:
the parallel component of a muscle force is larger than the perpendicular component for most muscles
true
98
check slides 52 and 53 still
okayyy
