Lesson Notes By Weeks and Term v4 - SHS 2
BASIC PHYSICS
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BASIC PHYSICS
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Subject: Physics
Class: SHS 2
Term: 1st Term
Week: 3
Grade code: 2.1.1.LI.2
Strand code: 1
Sub-strand code: 1
Content standard code: 2.1.1.CS.1
Indicator code: 2.1.1.LI.2
Theme: MECHANICS AND MATTER
Subtheme: BASIC PHYSICS
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This lesson explores why objects seem to lose weight or even float when placed in a fluid like water. We have all experienced this – a heavy bucket of water feels lighter when it's still inside a larger drum of water, or we feel lighter when swimming at Labadi Beach or in the Kpeshie Lagoon. This phenomenon is not magic; it is governed by a fundamental principle of physics discovered by the ancient Greek scientist, Archimedes. Understanding this principle helps us explain how massive fishing canoes on the Volta Lake and giant cargo ships at Tema Harbour can float. We will investigate the upward force, called upthrust or buoyant force, that fluids exert on objects.
This section breaks down the core ideas behind Archimedes' Principle. A. The Concept of Upthrust (Buoyant Force)
Whenever you place an object into a fluid (a liquid or a gas), the fluid pushes back on the object. This upward push is called upthrust or buoyant force. Why does upthrust occur? It happens because pressure in a fluid increases with depth. Consider a stone submerged in a bucket of water. The water at the bottom of the stone is deeper than the water at the top. Therefore, the pressure at the bottom is greater than the pressure at the top. Since Force = Pressure × Area, the upward force on the bottom surface of the stone is greater than the downward force on its top surface. The net result is an upward force – the upthrust. B. Stating Archimedes' Principle
This is the central rule that quantifies the upthrust.
> Archimedes' Principle states that when an object is wholly or partially immersed in a fluid, it experiences an upthrust that is equal in magnitude to the weight of the fluid it displaces.