Exam 2 - Completed by Anna at 6:45 PM Flashcards
1
Q
What is the definition of center of gravity?
A
The point of application of force due to gravity
2
Q
____ and _____ are concentrated at the center of gravity
A
weight and mass
3
Q
What is the point where all forces appear to act?
A
Center of gravity
4
Q
For an object to be in equilibrium, the sum of the torques around the body need to be _____
A
0
5
Q
What is the definition of line of gravity?
A
Line of application of gravity force
6
Q
Center of gravity of the body is the sum of what?
A
segment center of gravities
7
Q
Location of center of gravity of a human in normal standing position varies with what?
A
body build, age, and sex
8
Q
Female center of gravity is what?
A
55% of standing height
9
Q
Male center of gravity is what?
A
57% of standing height
10
Q
Why do women have a lower COG?
A
wider hips/pelvis
11
Q
COG is usually at which vertebrae?
A
Second sacral vertabrae
12
Q
COG of a combined segment is about ______ _____ COG of individual segments
A
halfway between
13
Q
COG helps facilitate ______.
A
motion
14
Q
COG alters _____ ____
A
exercise loads
15
Q
What are the 4 reasons to have a knowledge of COG?
A
Help facilitate motion, alter exercise loads, balance segments, and prevent falls
16
Q
When segments change position, so does what?
A
COG of body
17
Q
COG rises when what?
A
When you raise the height of your body
18
Q
When walking, the body has a _____ COG and ______ equilibrium
A
High
Unstable
19
Q
When walking what can cause displacement of the body?
A
small forces
20
Q
Walking is what?
A
a sequence of disturbing and catching COG
21
Q
People _____ COG for protection when there is uncertainty in control and balance
A
lower
22
Q
Uncertainty in control and balance may require what?
A
more energy
23
Q
Objects at rest = ?
A
equilibrium
24
Q
At equilibrium, force and torque = ?
A
0
25
All objects at rest are _________
not equally stable
26
When an object in stable equilibrium is disturbed, what happens?
It moves, but the COG will return to its initial position
27
What are some examples of objects in stable equilibrium?
weebles, rocking chair
28
What happens in unstable equilibrium?
COG is disturbed and finds new position
29
The new position of COG when an unstable object moves is what?
lower
30
What happens when an object is in neutral equilibrium?
COG does not fall or return to initial position
31
What is an example of a neutral object?
A ball
32
What are 4 factors affecting stability?
- Size and shape of base of support
- Height of COG above base of support
- Location of LOG within base of support
- Weight or mass of body
33
Which LOG location would have best stability?
central to base of support
34
The center of gravity in the base of support is more stable with a _____ base
larger
35
When in a staggered position, the COG has resistance to which forces?
AP forces
36
When feet are spread shoulder-width apart, COG has resistance to which forces?
lateral forces
37
Squatting position has more _______ ______
Lateral stability
38
More angular displacement can occur before COG goes ____ _____
beyond BOS
39
When LOG is within BOS, this = ?
equilibrium
40
Mass of body is only a factor when what?
when motion or an external force is involved
41
The greated the mass of the body, the _____ the stability
greater
42
what is mobility's relationship with stability?
inverse
43
What is the critical point?
change of state
44
What are important factors in mobility?
COG, LOG, BOS
45
What is force?
Entity which produces, halts, or changes direction of motion
46
How does force function?
Push or pull through contact or gravity
47
Force alters what?
the motion of body parts
48
Force = ?
mass*acceleration
49
W=?
mass * gravity
50
Weight is a force caused by what?
pull of gravity
51
What is load?
weight of an external object
52
What is strength?
the ability to lift or move weight
53
P=?
Force / Area
54
Force is a _____ ______
vector quantity
55
What are the aspects of force?
magnitude, point of application, line of application, direction
56
For a weight lifter to lift a 250 N barbell, what must they do?
apply a force greater than 250 N, in an upward direction, through the center of gravity of the barbell
57
What is newton's first law?
An object at rest remains at rest, object in motion remains in motion, unless acted on by a force
58
The acceleration of an object is directly proportional to what?
The force causing it and inversely proportional to the mass of the object
59
Heavier objects wil have a ______ acceleration
lower
60
What is newton's third law?
For every action force there is an equal and opposite reaction force
61
Injuries occur when you have what?
unequal forces
62
Pulleys are ____ or ____ systems
linear, concurrent
63
Pulleys can be in _____ or ____ positions
fixed, movable
64
What do pulleys do?
change the direction of force
65
What do single fixed pulleys do?
changes the line of action of force
66
single fixed pulleys have what mechanical advantage?
None
67
What is an example of a single fixed pulley?
cervical traction pulley
68
How do anatomical pulleys work?
Tendons deflected from straight course by bony prominences or soft tissue
69
What do anatomical pulleys do?
changes the angle of pull of muscle providing the force
70
Increase in angle of pull, increases what?
rotary component
71
When there is more force in the rotary component, there is more force in the ______ ______
osteokinematic motion
72
What are levers?
Rigid bars that can rotate about a fixed point when a force is applied to overcome a resistance
73
What are levers used to do?
- Overcome a resistance larger than the magnitude of the effort applied
- Increase the speed and range of motion through with a resistance can be moved
74
What are the 3 forces of levers?
axis/pivot, weight/resistance, moving/holding force
75
What are the moment arms of a lever?
effort arm, weight arm
76
What is the effort arm?
distance from pivot to force
77
What is the weight arm?
distance from pivot to weight
78
What is mechanical advantage?
Ratio between length of force arm and length of weight arm
79
MA=?
Force arm/ weight arm = Weight/ Force
80
A first class lever has what type of advantage?
force or distance
81
Where is the pivot on a first class lever?
Between the weight and force
82
A second class lever has what type of advantage?
force advantage
83
Where is the weight in a second class lever?
between the pivot and force
84
What is an example of a second class anatomical lever
hips
85
What kind of advantage does a 3rd class lever have?
distance advantage
86
Where is the force in a 3rd class lever?
between the pivot and weight
87
Which type of lever is the most prevalent in the body?
3rd class lever
88
In a 3rd class lever, how much force must you apply?
twice the force of the weight
89
When MA > 1, what type of advantage does the lever have?
force advantage
90
When MA < 1, what type of advantage does the lever have?
distance advantage
91
What is torque?
When a force is properly exerted on a rigid body pivoted about some axis, the body will tend to rotate about that axis
92
Torque is the tendency of what?
of a force to rotate a body about an axis
93
t = ?
r F sin f
94
d (moment arm) = ?
r sin f
95
Perpendicular distance from _____ to line of action of force
axis
96
clockwise torque =?
negative torque
97
counterclockwise torque = ?
positive torque
98
Torque in the arm is most when the resistance arm is where?
at 90 degrees from the LOG
99
Muscle forces that exert torque are dependent on what?
point of insertion of the muscle and length, tension, and angle of pull changes
100
What is Kinesiology?
the science dedicated to broad area of human movement
101
What are the subjects that are related to kinesiology?
sport psychology, motor learning, exercise physiology, biomechanics
102
Kinesiology is more ______ than biomechanics
qualitative
103
What is biomechanics
The application of principles and techniques of mechanics to structure, functions, and capabilities of living organisms
104
What subjects is biomechanics related to?
physics, chemistry, mathematics, physiology, and anatomy
105
Biomechanics is more _____ than kinesiology
quantitative
106
What is the purpose of the biomechanics of human movement?
describes, analyzes, and assesses human movement
107
biomechanics analyzes what?
a variety of movements, what is the same about them, and what changes
108
What is the definition of mechanics?
study of forces and their effects
109
What is the application of mechanical princlples to human and animal bodies in movement and at rest?
biomechanics
110
What are the 2 conditions of mechanics?
statics and dynamics
111
What are statics?
things that are not moving. Humans that are at-rest or moving with constant velocity. No acceleration. "Uniform Motion"
112
What are dynamics?
movement with acceleration/deceleration
113
What are the 2 areas of study in mechanics?
Kinematics and kinetics
114
What are kinematics?
the study of the effects/description of motion. displacement/velocity
115
What are kinetics?
The cause of motion. Deals with moving objects, and the forces that act to produce those motions
116
What are the 3 kinds of motion?
Linear, angular, and general
117
What is linear motion also known as?
translation
118
What is angular motion also known as?
rotary, rotation
119
What is general motion?
a combination of linear and angular motion
120
What limits the movement at the joints?
shape and fit
121
In linear motion, the ______ as a _____ is moved from one point to another
body as a whole
122
Any point on the object in linear motion can be used as a ______
reference point
123
In general, when an object is moving in linear motion, the parts ____________________________________
do not move relative to one another
124
What are the two types of linear motion?
rectilinear and curvilinear
125
What is rectilinear motion?
straight-line progression of the object
126
What is curvilinear motion?
Point on an object or body that moves in a linear fashion, but moved in a curved line
127
Objects moving in angular motion move around a _______
relatively fixed point
128
All points, regardless of how far they are from the pivot will what?
go through the same angle
129
Most of our joints go through what kind of motion?
general
130
Most projectiles move through what kind of motion?
general
131
What are the factors that determine linear motion?
The object is free to move
uniform force against the side of the object
force is direct to COG
Motion occurs unless there is resistance
132
What are the factors that determine angular motion?
Some portion fixed in place
Fulcrum or axis of rotation
force is applied to portion of the object that is free to move
133
What are biomechanics measured in?
metric system and english gravitational system
134
What is velocity measured in?
M/Sec^2
135
What is mass measured in?
slugs
136
What is force measured in?
lbs
137
What does linear kinematics measure?
distance and displacement
speed and velocity
acceleration
138
What is displacement?
change in position of an object
139
What must you know to measure displacement?
initial and final coordinates
140
Displacement is independent of a path if what?
end points are fixed
141
What is velocity?
the ratio of an object's displacement and time interval
142
Speed is the ______, velocity includes _____
number
| direction
143
What is average acceleration?
the ratio of change in velocity and time interval
144
Average acceleration is also said to be the rate at which you are what?
increasing or decreasing your speed
145
Different parts of the body have different ____ and _____
velocities and accelerations
146
velocity and acceleration depends on what?
how far the point is from the axis
147
Points near the axis have a displacement of _____ than those farther away
less
148
A point closer to the pivot has a smaller ______ ______
linear velocity
149
The furster a point is from the pivot point, the ______ its linear variables will be.
larger
