Stability and Equlibrium

1. Stability and Equlibrium By Dr Ajay Kumar Reader School of Physical Education DAVV Indore

2. Concept and Classification • Objects in equlibrium are classified according to the stability of that equlibrium. • If the position of an object is slightly altered and the objects tends to resurns its original position, the objects is in stable equlibrium. Stable

3. Unstable equilibrium exists when it takes only a slight push to destroy it.

4. The third classification of equilibrium is called neutral equilibrium and exist when an objects center of gravity is neither raised nor lowered when it is disturbed. A ball lying on floor is in neutral equilibrium.

5. Condition for Static Stability • The relation of line of gravity to the base of support. :- An objects retain its equilibrium only so long as its line of gravity falls within it base of support. • The height of center of gravity :- Stability is inversely proportional to the height of center of gravity.

6. Condition for Static Stability (cont) • The size and shape pf base of support :-Stability is directly proportional to base area • The mass of the body :-Stability is directly proportional to mass / weight of body • Friction :-Insufficient friction reduces the stability and vice - versa

7. Condition for Static Stability (cont) • Segmentation :-Maximum stability of a segmented body is assured when the center of gravity of all weight bearing segments lies in a vertical line which is centered over the base of support. • Visual and Psychological Factors :-When walking on a danger area the visual stimulus may affect the stability.

8. Condition for Static Stability (cont) • Physiological Factors :-The fluid found in the three semi-circular canal inside the ears is also responsible for stability.

9. Conditions of Dynamic Stability • For dynamic stability to exist there must be sufficient friction between shoo surface and playing surface. • In movement involving quick directional change on the ground an inward lean towards the changed direction is to be required to maintain dynamic stability.

10. When the body is free in air to move the balance or the stability can be maintained by the application of end and middle. • When either feet and hand are supported during a movement the stability can be maintained by shifting the hips or other unsupported body parts.

11. Majority of the times dynamic stability or equilibrium is obtained involuntarily by the physiological mechanism governing posture and equilibrium, which includes kinesthetic perception and certain body reflexes.

12. Principles of Stability • Principle I :- Other things being equal the lower the center of gravity the greater will be the stability. • Principle II :- Greater stability is obtained if the base of support is widened in the direction of the line of force.

13. Principle III :-For maximum stability the line of gravity should intersect the base of support at a point which will allow greatest range of movement within the area of the base in the direction of force causing motion.

14. Principle IV :- Other things being equal, the greater the mass of the body greater will be the stability. • Principle V :- Other things being equal the most suitable position of a vertical segmented body is one in which the center of gravity of each weight bearing segments lies in a vertical line centered over the base of support

15. Principle VI :- The other things being equal, the greater the friction between the supporting surface and part of the body or shoo in contact the more stable body will be. • Principle VII :- Other things being equal, a person has better balance in locomotion under difficult circumstances when he focuses his vision on stationary objects rather than on disturbing stimulus.

16. Principle VIII :- There is a positive relationship between one’s physical and emotional state and the ability to maintain stability under difficult circumstances. • Principle IX :- Regaining equilibrium is based on same principles as maintaining.