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: 9
Grade code: 3.1.1.LI.5
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.3
Indicator code: 3.1.1.LI.5
Theme: MECHANICS AND MATTER
Subtheme: BASIC PHYSICS
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Welcome, students! For thousands of years, Ghanaians, like all people around the world, have looked up at the night sky with wonder. We see the Moon, countless stars, and sometimes, a sudden streak of light—a "shooting star." These celestial objects are not just beautiful; they are part of our story. They have influenced our farmers, our fishermen, our storytellers, and our traditions. In this lesson, we will bridge the gap between ancient wonder and modern physics. We will learn the scientific identity of these objects—comets, asteroids, meteors—and explore how they have shaped, and continue to shape, our culture and society right here in Ghana and across the world.
This section breaks down the celestial objects we need to understand. We will use analogies to make the concepts easier to remember.
A. Asteroids: The "Space Rocks" Definition: An asteroid is a large, irregularly shaped rock, often containing metals, that orbits the Sun. Composition: Primarily made of rock (silicates) and metals (like iron and nickel). They are like giant, leftover building materials from when our solar system was formed. Location: Most asteroids are found in the Asteroid Belt, a region of space located between the orbits of Mars and Jupiter. Size: They can range in size from a few metres across to nearly 1,000 kilometres in diameter (like the dwarf planet Ceres). Analogy: Think of asteroids as the *gravel and chippings* left over after building a big house (the solar system). Most of this leftover material is found in one area—the Asteroid Belt.
B. Comets: The "Dirty Snowballs" Definition: A comet is a celestial body made of ice, dust, and rock that orbits the Sun. Composition: A mixture of water ice, frozen gases (like carbon dioxide, methane, and ammonia), rock, and dust. The name "dirty snowball" is a very accurate description. Location: Most comets come from the very distant, cold regions of our solar system: the Kuiper Belt (beyond Neptune) and the Oort Cloud (a vast, spherical cloud surrounding the solar system). Key Features: When a comet's orbit brings it close to the Sun, the heat causes the ice to sublimate (turn directly from solid to gas). This process creates: A Coma: A glowing, hazy cloud of gas and dust that forms around the comet's nucleus (the solid part). Two Tails: The solar wind and radiation push the gas and dust away, forming two distinct tails that always point away from the Sun: A straight, bluish ion (gas) tail. A curved, whitish dust tail. Analogy: Imagine a ball of frozen gari soakings mixed with dust. When you bring it close to a hot fire (the Sun), it starts to steam and trail a cloud of gari and dust particles behind it. That cloud is like the coma and tails.
C. The Meteoroid Family: A Journey in Three Parts