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: 5
Grade code: 3.1.1.LI.2
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.2
Indicator code: 3.1.1.LI.2
Theme: MECHANICS AND MATTER
Subtheme: BASIC PHYSICS
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My dear students, welcome to today's lesson. Have you ever wondered why a ripe mango from a tree always falls straight down to the Earth, but the Moon, which is also pulled by Earth's gravity, never falls down on us? This seems like a puzzle, but Physics gives us the tools to understand it. Today, we will explore the very force that governs these motions: Gravity. We will act like scientific detectives and connect two very important ideas in physics: The force that gives an object its weight here on Earth (`Weight = mg`). The universal force of attraction that exists between any two objects in the universe (`F = GmM/r²`).
This lesson is built on two foundational laws described by Sir Isaac Newton. Let us break them down first. Concept 1: Weight and Local Gravity (`g`)
From Newton's Second Law of Motion (`F = ma`), we know that a force (`F`) applied to a mass (`m`) causes it to accelerate (`a`).
When an object is near the surface of the Earth, the force pulling it down is its weight (`W`). The acceleration it experiences (if we ignore air resistance) is the acceleration due to gravity, which we represent with the symbol `g`.
So, we can write the formula for weight as: `W = m * g` `W` is the weight in Newtons (N). `m` is the mass of the object in kilograms (kg). `g` is the acceleration due to gravity in metres per second squared (m/s²).