VII. Case Study 1: During her gymnastics practice, Zoya was finding it difficult to maintain her balance on th

8.5 — Case Study Questions

Q. VII. Case Study 1: During her gymnastics practice, Zoya was finding it difficult to maintain her balance on the balancing beam. Her coach tried to explain to her the basic principles of equilibrium. According to the principles of equilibrium, Centre of Gravity plays a very important role. a. ___________ C.G helps in increasing stability. b. __________ base more stability. c. There are two types of equilibrium namely _________ and ___________.

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Concept understanding — Equilibrium Types

Equilibrium Types

Balance a pencil on its point, and the smallest breath of air sends it toppling. Rest a ball at the bottom of a bowl, and no matter how you nudge it, it rolls back to the centre. Both objects are technically "balanced," but they behave completely differently when disturbed — and that difference is exactly what the three types of equilibrium describe in biomechanics.

The Three Types

Stable equilibrium describes a body that, when disturbed slightly, tends to return to its original position. This happens when the body's centre of gravity is low and its base of support is wide — like a wrestler crouched in a low stance, or a sprinter in the set position before a race. Push it slightly, and the forces at work pull it back toward balance.

Unstable equilibrium describes a body that, when disturbed even slightly, moves further away from its original position rather than returning to it. This happens when the centre of gravity is high relative to a narrow base of support — a gymnast balanced on one foot on a beam, or a handstand, where the smallest shift can cause a fall unless constantly corrected.

Neutral equilibrium describes a body that, when disturbed, simply settles into a new position without any tendency to return to the old one or move further away — like a ball rolling on a flat, level surface. It does not seek its old spot back, nor does it run away from it; it is equally "balanced" wherever it ends up.

Important

The type of equilibrium a body is in depends on the height of its centre of gravity and the size of its base of support relative to that centre of gravity — the same two factors that determine overall stability. A lower centre of gravity and a wider base push a position toward stable equilibrium; a higher centre of gravity and a narrower base push it toward unstable equilibrium.

Why It Matters in Sport

An athlete deliberately chooses which type of equilibrium suits the moment. A rugby player about to be tackled lowers their centre of gravity and widens their stance to become more stable and harder to knock over. A high jumper, by contrast, needs to leave a stable position quickly and become momentarily unstable in the air to rotate over the bar. A gymnast on a balance beam is constantly fighting to stay near stable equilibrium despite a very narrow base of support, which is precisely why the skill is so demanding — the margin between staying balanced and falling is razor-thin.

Note

Equilibrium types are not fixed properties of a sport or a person — they describe a specific body position at a specific moment. The same athlete can move between stable and unstable equilibrium many times within a single movement, such as a wrestler shifting from a stable stance into an unstable, off-balance position to execute a throw.

Zoya's balance problem is explained directly by the chapter's stability principles — a lower centre of gravity and a broader base both increase stability, and equilibrium itself splits into static and dynamic types.

a. The chapter's guiding principle states: 'Lower the Centre of gravity, higher the stability' — bringing the CG down (bending the knees, lowering the body) increases stability. A gymnast on a beam who raises their arms/legs to shift the CG, or keeps it low and centred, is applying exactly this principle.

b. Another guiding principle: 'Broader the base, the greater the stability' — a wider base of support (e.g., spreading the feet) makes a stance harder to upset. On a narrow beam, a gymnast has an inherently small base of support, which is precisely why balance is so difficult — the beam itself limits how broad the base can be.

c. The chapter names exactly two types of equilibrium: Static equilibrium (the body is not moving or rotating; all forces and torques sum to zero) and Dynamic equilibrium (the body moves with unchanging speed and direction).

✓Final answer

a. Lower. b. Broader/wider. c. Static and Dynamic equilibrium.

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