Lesson Notes By Weeks and Term v4 - SHS 1
INTRODUCTION TO PHYSI CS
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INTRODUCTION TO PHYSI CS
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Subject: Physics
Class: SHS 1
Term: 1st Term
Week: 3
Grade code: 1.1.1.LI.2
Strand code: 1
Sub-strand code: 1
Content standard code: 1.1.1.CS.2
Indicator code: 1.1.1.LI.2
Theme: MECHANICS AND MATTER
Subtheme: INTRODUCTION TO PHYSI CS
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Welcome, future scientists and engineers! Today, we are learning about the fundamental "language" of physics: Dimensional Analysis. Think of it like learning the grammar of a language. If you know the grammar, you can check if a sentence makes sense. In physics, if we know the dimensions of quantities, we can check if our equations and formulas make sense. This is a powerful tool used by everyone from the engineer building the new Pokuase interchange to the pharmacist determining the correct medicine dosage. It helps us ensure our calculations are not just numbers, but are physically meaningful.
Part A: Physical Quantities - Base vs. Derived
A physical quantity is any property of a material or system that can be quantified by measurement. For example, the length of your exercise book, the time it takes to walk from the classroom to the assembly hall, or the mass of a bag of gari.
In physics, we group these quantities into two main types: Base (or Fundamental) Quantities: These are the basic building blocks. They are independent and do not depend on any other quantity for their definition. In mechanics, the three we will focus on are: Mass: The amount of matter in an object. Length: The measure of distance between two points. Time: The duration or interval between events. *(Note: There are other base quantities like Temperature, Electric Current, etc., but for mechanics, Mass, Length, and Time are our foundation).* Derived Quantities: These are quantities that are formed by combining base quantities through multiplication, division, or both. They "derive" their meaning from the base quantities. Example 1: Area. To find the area of your classroom floor, you multiply its length by its width. Both length and width are base quantities of Length. So, Area is a derived quantity. Example 2: Speed. To find the speed of a car, you divide the distance it travelled (Length) by the time it took (Time). So, Speed is a derived quantity. Part B: Dimensions
The dimension of a physical quantity is a way of expressing its nature in terms of the base quantities. We use specific symbols to represent the dimensions of our three base quantities: Dimension of Mass is represented by [M] Dimension of Length is represented by [L] Dimension of Time is represented by [T]