The Center of Gravity and Stability

Question 1

Center of Gravity

Answer 1

The point where all the weight of the body/object is concentrated

Question 2

The center of gravity is the point where all the forces acting on the body equal _.

Answer 2

0

Question 3

True or false: The center of gravity remains in the same location regardless of changes in body position

Answer 3

False. If the shape or position changes, the location of the center of gravity also changes, possibly even outside of the body.

Question 4

In a standing female, the COG is about __% of standing height.

Answer 4

55

Question 5

In a standing male, the COG is about __% of standing height

Answer 5

57

Question 6

In quiet standing, the COG can be considered almost directly over the _______ __ _______

Answer 6

Center of pressure

Question 7

Define the center of pressure

Answer 7

Point at which the force vector for ground reaction force is applied

Question 8

Postural sway

Answer 8

As the COG shifts slightly, the COP will shift slightly in the foot-ground interface

Question 9

There is _______________ sway in the sagittal plane of about 2-3cm.

Answer 9

Anteroposterior (AP)

Question 10

There is ______________ sway in the frontal plane of about 1-2cm.

Answer 10

Mediolateral (ML)

Question 11

An object at rest is in __________ with all forces acting upon it being __________.

Answer 11

equilibrium; balanced

Question 12

True or False: An object at rest is stable.

Answer 12

False. An object at rest may or may not be stable.

Question 13

An object placed so that an effort to disturb it would require its COG to be raised is in _______ equilibrium.

Answer 13

Stable

Question 14

An object placed so that only a slight push will drop the object’s COG to a lower point is in _______ equilibrium.

Answer 14

Unstable

Question 15

An object whose COG is neither raised nor lowered when disturbed is in ______ equilibrium.

Answer 15

Neutral

Question 16

True or False: Human beings spend most of their time adjusting body positions for the type of equilibrium best suited to the task.

Answer 16

True

Question 17

8 Factors that affect stability

Answer 17

Size/shape of base of support
Height of the COG
Relation of the line of gravity to the base of support
Mass of the body
Friction
Segmental alignment
Visual/Psychological factors
Physiological factors

Question 18

The ___________ is the part of the body in contact with the supporting surface and intervening area.

Answer 18

base of support

Question 19

As the base of support increases in size, the stability increases/decreases.

Answer 19

increases

Question 20

To resist lateral external forces, the base of support should be widened toward/away from the direction of the oncoming force.

Answer 20

toward

Question 21

A high/low COG increases stability.

Answer 21

Low

Question 22

Why does a low COG increase body stability?

Answer 22

Because it allows greater angular displacement of the COG within the bounds of the base of support

Question 23

The nearer/further the line of gravity to the center of the base of support, the greater the stability.

Answer 23

Nearer

Question 24

Where must the COG go when a human begins to rotate about an axis?

Answer 24

Outside of the base of support

Question 25

When a lateral external force acts on the body, stability increases/decreases if the line of gravity remains over the base even when forced to move by the force.

Answer 25

increases

Question 26

Other things being equal, the greater the mass of a body, the greater/lesser will be its stability.

Answer 26

greater

Question 27

Other things being equal. the most stable position of a vertical segmented body is one in which the COG of each weight-bearing segment lies in a horizontal/vertical line centered over the base of support.

Answer 27

vertical

Question 28

Other things being equal, the greater the friction between the supporting surface and the body parts in contact with it, the more/less stable the body will be.

Answer 28

more

Question 29

Other things being equal, a person has better balance in locomotion under difficult circumstances when the vision is focused on stationary objects/disturbing stimuli.

Answer 29

stationary objects

Question 30

True or false: it is easier to maintain balance under difficult circumstances when one’s physical and emotional state are intact.

Answer 30

True

Question 31

True or False: regaining equilibrium is based on the same principles as maintaining it

Answer 31

True