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Concepts in Physics

Center of GravityCenter of Gravity

The point in the body or object that its weight is balanced around

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Changes when weights or objects are attached to body

Center of Gravity Changes With Changes in Body Position

Line of GravityLine of Gravity

An imaginary vertical line that runs through the center of gravity

An object is most stable when the line of gravity passes through its base of support

Line of Gravity Must Fall Within the Base of Support

Base of SupportBase of Support

The two-dimensional area between and including an object’s points of contact with the supporting surface

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Changing Base of Support for Stability

StabilityStability

An object is most stable when the line of gravity stays within the base of support.

The larger the base of support, the more stable the object.

Stability is greater when the base of support is positioned in alignment with the direction of force application.

DefinitionsDefinitions

CreepStructural fatigue

Friction

Torque

Endurance limit; fatigue failureCumulative-trauma injuries vs. acute-trauma injuries

DefinitionsDefinitions

Strength

Work

Power

Use of Frictionin Therapeutic Exercise

Definitions- Class DefinedDefinitions- Class Defined

Potential energyKinetic energy

Physiological Muscle Advantages

Multi-joint Muscles

Summation of Forces

Energy

(continued)

Definitions –Class DefinedDefinitions –Class Defined

Velocity

Acceleration and deceleration

Elasticity

Stress and strain

(continued)

Hooke’s lawStress-strain curve

Definitions –Class DefinedDefinitions –Class Defined

Inertia

Acceleration and Momentum

Action-Reaction

1st-3rd class levers