🔹 Statement of Archimedes’ Principle
👉 “When a body is wholly or partially immersed in a fluid, it experiences an upward force (upthrust) equal to the weight of the fluid displaced by it.”
This upward force is called buoyant force and is responsible for the floating or apparent loss of weight of objects in fluids.
🔹 Demonstration of Archimedes’ Principle
Activity:
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Take a solid object and measure its weight in air using a spring balance.
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Immerse the object fully in a container of water while still attached to the spring balance.
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You will observe that the weight reading decreases.
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Collect the displaced water in a measuring jar and find its weight.
Observation:
The loss in weight of the object = weight of displaced water.
This verifies Archimedes’ Principle.
🔹 Mathematical Expression
Fb=ρ g V
Where,
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Fb= Upthrust (buoyant force)
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ρ= Density of the fluid
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g = Acceleration due to gravity
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V = Volume of fluid displaced
🔹 Daily Life Applications of Archimedes’ Principle
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Floating of Ships – Ships float because the upthrust equals the weight of water displaced, even though ships are made of heavy metals.
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Hydrometer – Works on Archimedes’ principle to measure the density of liquids.
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Hot Air Balloons – Rise in the air because the buoyant force of air is greater than the weight of the balloon.
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Submarines – Control their depth by regulating the volume of water in ballast tanks, adjusting the upthrust.
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Apparent Loss of Weight – Objects appear lighter when immersed in water due to upthrust.
✅ Conclusion
Archimedes’ Principle explains the concept of upthrust and buoyancy. It is the foundation for understanding why objects float or sink and is applied in designing ships, submarines, hydrometers, and balloons.