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: 6
Grade code: 3.1.1.LI.4
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.2
Indicator code: 3.1.1.LI.4
Theme: MECHANICS AND MATTER
Subtheme: BASIC PHYSICS
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This lesson challenges our everyday understanding of weight. We often think of weight as something constant, but is it? We've all seen videos of astronauts floating effortlessly in space. Are they without weight because they are far from Earth, or is something else happening? This lesson explores the fascinating concept of weightlessness. Understanding this principle is fundamental not only for space exploration but also for understanding the physics of motion, forces, and gravity that govern satellites providing our TV signals (like DSTV) and GPS for our phones. It helps us see that physics is not just in textbooks but is at work all around us and far above our heads.
Part 1: Revisiting Mass and Weight
Before we can understand weightlessness, we must be absolutely clear on the difference between mass and weight. This is a common point of confusion. Mass (m): Definition: The amount of matter or "stuff" in an object. Unit: kilogram (kg). Nature: It is a scalar quantity and is constant no matter where the object is in the universe. Your mass is the same on Earth, on the Moon, or in deep space. Weight (W): Definition: The force of gravity acting on an object's mass. Unit: Newton (N). Nature: It is a vector quantity (it always acts towards the centre of the celestial body, e.g., Earth). It is not constant; it depends on the gravitational field strength (`g`). Formula: W = m × g Where `g` on Earth is approximately 9.8 m/s² (we often use 10 m/s² for easier calculations in WASSCE).