3 Concepts in Physics

Center of Gravity The point in the body or object that its weight is balanced around Changes with movement as the position of the extremities is changed Changes when weights or objects are attached to body The lower the center of gravity, the more stable the object

Center of Gravity Changes With Changes in Body Position

Line 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 Support The two-dimensional area between and including an object’s points of contact with the supporting surface A larger base of support provides more stability than a narrow base of support

Changing Base of Support for Stability

Stability 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.

Definitions Creep Structural fatigue Endurance limit; fatigue failure Cumulative-trauma injuries vs. acute-trauma injuries Friction

Use of Friction in Therapeutic Exercise

Definitions- Class Defined Strength Work Power Energy Potential energy Kinetic energy (continued)

Definitions –Class Defined Velocity Acceleration and deceleration Elasticity Stress and strain Hooke’s law Stress-strain curve (continued)

Definitions –Class Defined Inertia Acceleration and Momentum Action-Reaction 1st-3rd class levers