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: 4
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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Welcome, future scientists and engineers! In our last lesson, we learned how to check if a physics equation is correct using the powerful tool of dimensional analysis. Today, we will take this a step further. We will learn how physicists can *predict* the form of an equation even before doing a single experiment! This is not magic; it is the logical power of dimensions. Imagine you are an engineer tasked with building a bridge over the Volta River. You need to know how the force on a pillar depends on the speed of the water, the water's density, and the size of the pillar. Dimensional analysis gives you a starting point to figure out this relationship.
Recap: The Principle of Dimensional Homogeneity
Before we derive new equations, let's remember the fundamental rule we learned last time. The Principle of Dimensional Homogeneity states that for any valid physical equation, the dimensions of all the terms on both sides of the equation must be the same. For example, in `v = u + at`, the dimensions of `v`, `u`, and `at` must all be `[LT⁻¹]`. We will use this principle as our main tool today. The Method: Deriving Equations Step-by-Step
To establish a relationship between quantities, we follow a systematic procedure. Let's say we suspect a quantity `Q` depends on three other quantities `X`, `Y`, and `Z`.
Step 1: Assume a Proportionality We start by assuming a relationship of the form: `Q ∝ Xᵃ Yᵇ Zᶜ` Here, `a`, `b`, and `c` are unknown powers (exponents) that we need to find.