Lesson Notes By Weeks and Term v4 - SHS 3
BASIC PHYSICS
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BASIC PHYSICS
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Subject: Physics
Class: SHS 3
Term: 1st Term
Week: 2
Grade code: 3.1.1.LI.3
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.1
Indicator code: 3.1.1.LI.3
Theme: MECHANICS AND MATTER
Subtheme: BASIC PHYSICS
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Welcome, future scientists and engineers! Today, we are exploring a fundamental concept that is all around us, from the mighty Adomi Bridge standing firm over the Volta River to a kayayo skillfully balancing a load on her head in Makola Market. This concept is called Equilibrium. It is the principle of balance. Understanding equilibrium is crucial not just for passing WASSCE, but for understanding how structures are built, how we maintain our posture, and how many objects in our world remain stable and useful. This lesson will equip you with the foundational knowledge to analyse and predict the stability of objects under the influence of various forces.
A. What is Equilibrium?
In simple terms, equilibrium is a state of balance. In Physics, a body is said to be in equilibrium if its state of motion is not changing. This means the body is either: At rest (not moving at all). This is called Static Equilibrium. Moving with a constant velocity (constant speed in a straight line). This is called Dynamic Equilibrium.
Example: Static Equilibrium: A textbook resting on a table. The forces on it (gravity pulling down, table pushing up) are balanced. Dynamic Equilibrium: A trotro travelling at a constant 60 km/h on a straight, level stretch of the Accra-Kumasi highway. The forward force from the engine is perfectly balanced by the backward forces of air resistance and friction. Since the net force is zero, the trotro does not accelerate.
For a body to be in *complete* equilibrium, it must satisfy two important conditions. If even one of these conditions is not met, the body will either accelerate linearly (change its straight-line motion) or accelerate angularly (start to spin or rotate). B. The Two Conditions for Equilibrium First Condition: Translational Equilibrium (Balance of Forces)