“A lower centre of gravity and a wider base of support increase stability.” Justify this statement with exampl

Concept understanding — Center of Mass Stability

Center of Mass Stability

Think about a toddler learning to walk. They stand with their feet wide apart, arms out, wobbling. They fall often. Now think of a sumo wrestler — low to the ground, legs spread, solid as a rock. What's the difference? It's not just practice. It's physics, and the key idea is center of mass stability.

The Intuition: The Balancing Point

Every object, including your own body, has a single point where its entire weight seems to be concentrated. That point is the center of mass. For a perfectly symmetrical object like a ball, it's right at the geometric center. For a human standing straight, it's roughly around your navel.

Now, stability is about whether that point stays inside your base of support — the area beneath you that is in contact with the ground. If your center of mass moves outside that base, you tip over. That's why a toddler falls: their center of mass is high (they're tall relative to their width) and their base is narrow (feet close together). A slight lean shifts the center of mass past their feet, and gravity does the rest.

Note

The base of support isn't just the area of your feet. If you use a walking stick, your base expands to include the area between your feet and the stick's contact point. That's why a stick helps you balance — it enlarges your stable zone.

What Makes Something Stable?

Three factors determine how stable an object is:

Height of the center of mass: Lower is more stable. A racing car is built low to the ground so it doesn't flip in a sharp turn. A tall lamp is easy to knock over because its center of mass is high.
Size of the base of support: Wider is more stable. A four-legged chair is harder to tip than a two-legged one. A person standing on one leg is less stable than on two.
Position of the center of mass relative to the base: The closer it is to the center of the base, the more stable. If you lean forward while standing, your center of mass moves toward the front of your feet. Lean too far, and you must step forward to catch yourself — you've moved your base under your shifting center of mass.

Important

Stability is not about being heavy. A heavy object with a high center of mass and a narrow base can be less stable than a light object that is low and wide. Think of a heavy vase on a thin pedestal versus a light, flat book on a table.

Why It Matters in Everyday Life …

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Stability in sports is maximised when the centre of gravity is low and the base of support is wide — this principle governs balance in static and dynamic athletic positions.

This statement is a direct application of the physics of equilibrium to human movement. In any sport, an athlete’s stability — their ability to resist being knocked off balance or to maintain control during motion — depends on two key factors: the height of their centre of gravity (COG) and the size of their base of support (BOS). The COG is the point where the body’s mass is concentrated; in a standing human, it lies roughly at the level of the navel. The BOS is the area enclosed by all points of contact with the ground — feet, hands, or equipment.

When the COG is lower, the line of gravity (a vertical line dropped from the COG) falls closer to the centre of the BOS, making it harder for an external force to tip the athlete over. A wider BOS means that the line of gravity can shift further in any direction before it leaves the base, giving the athlete a larger margin of error before they lose balance. Together, a low COG and a wide BOS create a stable equilibrium — the athlete can absorb and redirect forces without falling.

Consider a wrestler in a defensive stance. They crouch low, bending their knees and spreading their feet shoulder-width apart or wider. This lowers their COG toward the mat and broadens their BOS. When an opponent tries to push or pull them, the wrestler’s line of gravity stays well inside the wide base, so they can resist the force and counterattack. A wrestler who stands upright with feet together is easily toppled because the COG is high and the BOS is narrow.

In basketball, a defender guarding an opponent does the same: knees bent, feet wide, arms out. This low, wide stance lets them slide laterally and absorb contact without losing balance. A player who stands tall with feet close together gets beaten on a crossover dribble or pushed off their spot. …

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Q.“A lower centre of gravity and a wider base of support increase stability.” Justify this statement with examples from sports.

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