What are the laws of Floatation? | Lucent for GK - UPSC PDF Download

Introduction

Floatation is a mesmerizing property exhibited by objects when they are immersed in a fluid, typically water. The ability of an object to float or sink depends on its density, which is a measure of mass per unit volume. When the density of an object is lower than the density of the surrounding fluid, it experiences an upward force known as buoyant force, allowing it to float. The principle of floatation was first articulated by Archimedes, a brilliant mind of ancient Greece.

The Laws of Floatation

Archimedes's groundbreaking discoveries led to the formulation of the fundamental laws of floatation. Let's explore these laws, which unravel the mysteries of buoyancy and equilibrium:

Law of Buoyancy

According to Archimedes, when an object is submerged in a fluid, it experiences an upward force equal to the weight of the fluid it displaces. This buoyant force enables the object to float if the weight of the fluid it displaces matches the weight of the object itself. Thus, the law of buoyancy states that for an object to float, it must displace a volume of fluid with a weight equal to its own weight.

Density Determines Floatation

Density plays a pivotal role in determining whether an object will float or sink. If the density of an object is less than or equal to the density of the fluid it is immersed in, it will float. For instance, a leaf effortlessly rests atop the water because its density is lower than that of water. Conversely, a stone sinks due to its higher density compared to water.

Examples and Applications

Floatation manifests in numerous real-life scenarios, offering captivating examples and practical applications. Let's explore a few:

• The Mystery of the Floating Ship: Ever wondered how colossal ships weighing tons manage to float? The secret lies in their structure. Although ships are primarily constructed from heavy materials such as iron and steel, they possess substantial air-filled spaces. These spaces enable the ship to displace water with a weight equal to its own, thus floating effortlessly.
• The Plight of the Sinking Needle: On the other end of the spectrum, a needle sinks despite its minuscule weight. The needle displaces more water than its own weight, causing it to sink. Unlike ships, the needle lacks the buoyancy-enhancing air-filled spaces, resulting in its swift descent.

Understanding the Center of Buoyancy and Meta Centre

To comprehend the intricate dynamics of floatation, it is essential to grasp the concepts of the center of buoyancy and meta centre:

Center of Buoyancy

The center of gravity of the liquid displaced by an immersed body is referred to as the center of buoyancy. This center plays a crucial role in determining the stability and equilibrium of a floating object.

Meta Centre

When a floating body tilts slightly from its equilibrium position, the center of buoyancy shifts. The point at which the vertical line passing through the new position of the center of buoyancy intersects with the initial line is known as the meta centre. The meta centre's position influences the stability of the floating object.

Stable Equilibrium for Floating Bodies

For a floating body to maintain stable equilibrium, certain conditions must be met:

• The meta centre must always be positioned higher than the body's center of gravity.
• The line connecting the body's center of gravity and the center of floatation should be vertical, ensuring stability.

Fascinating Facts and Further Insights

Floatation holds many captivating facts and additional insights that deepen our understanding:

• The Density of Seawater: The density of seawater is higher than that of normal water, resulting in a different floatation experience for swimmers in the ocean.
• The Enigmatic Ice Floats: When ice floats on water, approximately only one-tenth of its total volume is visible above the water surface, while the remaining nine-tenths remain submerged.
• Melting Ice's Impact: If ice floating in a vessel melts, the water level within the vessel does not change. This phenomenon occurs because the volume of water displaced by the ice is already equivalent to the volume of the melted ice.
• Measuring Purity with a Lactometer: The purity of milk can be measured using a device called a lactometer, which utilizes the principles of floatation.