Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Define basic and derived physical quantities.
• Determine the dimensions of quantities like velocity, force, and energy.
• Identify relationships between different physical quantities.
• Calculate the units of measurement for dependent quantities.

Lesson summary

Physics is the study of the fundamental principles governing the universe, from the smallest particles to the largest galaxies. To describe these principles, we must first be able to measure things accurately. In Ghana, whether we are an engineer building a bridge over the Volta River, a nurse at Korle-Bu calculating a patient's dosage, or a trader at Makola market weighing bags of rice, we deal with physical quantities. This lesson introduces a powerful tool called dimensional analysis, which helps us understand the fundamental nature of these quantities.

Lesson notes

2.1 Physical Quantities: Base vs. Derived

A physical quantity is any property of a material or system that can be quantified by measurement. We group them into two types: Base (or Fundamental) Quantities: These are the basic building blocks of all other physical quantities. They are independent of one another. Think of them as the letters of the alphabet in physics. There are seven internationally agreed-upon base quantities. Derived Quantities: These are quantities that are formed by combining base quantities through multiplication, division, or both. Think of them as the words we form using the letters of the alphabet. For example, Speed is derived from Length (distance) and Time. 2.2 The Seven Base Quantities and Their Dimensions

A dimension is the fundamental nature of a physical quantity. It tells us what kind of quantity it is, without regard to the specific unit used to measure it. For example, the distance from Accra to Kumasi, the height of a student, and the width of this page all have the dimension of Length, even though they are measured in kilometres, metres, and centimetres.

We represent dimensions with specific symbols, usually a capital letter in square brackets `[ ]`.

Evaluation guide

• Determine the dimensions of physical quantities (velocity, acceleration, mass, lengt h,
• time, weight, energy, force).
• Collaborative learning :
•  Let learners identify the relationship between quantities such as density, speed/velocity,