Archimedes’ Principle: Forces of Fluids and Buoyancy

14 Dec 2023

Archimedes’ Principle in Fluid Mechanics:

Archimedes’ Principle, formulated by the ancient Greek mathematician and scientist Archimedes, states that a body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. Archimedes’ insight, famously demonstrated in his “Eureka” moment, laid the groundwork for understanding fluid mechanics and has widespread applications, from ship design to the functioning of hot air balloons. The principle remains a cornerstone in physics, particularly in the study of fluids and floating bodies.

Archimedes’ Principle: Fluid Forces and Real-World Implementations:

  • Buoyant Forces: Dynamics of submerged bodies in Fluids: Whenever a body is completely or partially submerged in a fluid, it experiences an upward force. 
    • This force is equivalent to the weight of the fluid that the body displaces. 
  • Fluid Displacement Equivalence in Archimedes’ Principle: Unchanging Buoyant Force: This principle answers why there’s no further decrease in elongation once the stone is fully submerged, the amount of displaced fluid remains constant, and thus the buoyant force does not increase further.
  • Archimedes’ Principle: Weight loss equation in Fluid Submersion: This principle can be summarized as ‘the loss of weight of a body submerged (partially or fully) in a fluid is equal to the weight of the fluid displaced’
  • Practical Applications of Archimedes’ Principle: From Marine Design to Precision Instruments:
  • Archimedes’ principle is fundamental in designing marine structures such as ships and submarines. 
  • Instruments like lactometers (measuring milk purity) and hydrometers (determining liquid densities) also operate based on this principle.

Archimedes’ Principle in Action: A Stone’s immersion experiment and Buoyancy:

  • A stone is tied to a rubber string or a spring balance .
  • The stone is suspended, causing elongation in the string or a specific reading on the spring balance due to the stone’s weight.
  • The stone is gradually immersed in water. 
  • As it gets submerged, the elongation of the string or the reading on the spring balance decreases.
Archimedes' Principle
(a) Observe the elongation of the rubber string due to the weight of a piece of stone suspended from it in air. (b) The elongation decreases as the stone is immersed in water.

Buoyancy: Observing changes in elongation as a Stone immerses in water: 

  • The elongation or the reading decreases as the stone is immersed in water, with no further change once the stone is fully submerged.

Buoyant Forces: Dynamics of stone immersion and Archimedes’ Principle:

  • The elongation in the string or the spring balance reading is a result of the stone’s weight. 
  • When this elongation or reading decreases upon immersion in water, it suggests an upward force acting on the stone. 
  • This force, which opposes the stone’s weight and results in decreased tension on the string or spring balance, is termed the buoyant force or force of buoyancy.

Archimedes

Archimedes

  • Archimedes was a renowned Greek scientist who discovered the principle now named after him. 
  • This principle further aided him in verifying the purity of a gold crown meant for the king. 
  • Apart from this, Archimedes is acclaimed for his contributions to geometry and mechanics. 
  • His profound understanding of mechanisms like levers, pulleys, and wheels-and-axle notably benefited the Greek army during their confrontations with the Romans.

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UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
Integration of PYQ within the booklet
Designed as per recent trends of Prelims questions
हिंदी में भी उपलब्ध

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