Lesson Notes By Weeks and Term v4 - SHS 2
MATTER
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MATTER
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Subject: Physics
Class: SHS 2
Term: 1st Term
Week: 6
Grade code: 2.1.2.LI.2
Strand code: 1
Sub-strand code: 2
Content standard code: 2.1.2.CS.1
Indicator code: 2.1.2.LI.2
Theme: MECHANICS AND MATTER
Subtheme: MATTER
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Welcome, students! Today, we are exploring a fundamental property of matter called elasticity. Have you ever stretched a rubber band to shoot a piece of paper? Or noticed how the suspension on a `tro-tro` bounces when it hits a pothole on a Ghanaian road? Or seen a trader at Makola Market weighing yams with a spring balance? All these everyday experiences are governed by a simple but powerful principle known as Hooke's Law. Understanding this law helps us design everything from comfortable car seats and mattresses to strong, safe buildings and bridges. We will investigate how materials stretch and what limits they have before they break or get permanently damaged.
A. Elasticity and Elastic Materials Elasticity is the ability of a material to deform (change its shape or size) when a force is applied to it and to return to its original shape and size after the force is removed. Elastic Materials: Materials that show this property, e.g., a spring, a rubber band, a steel ruler. Plastic Materials: Materials that do not return to their original shape after the deforming force is removed, e.g., modelling clay (plasticine), putty, dough. When a material is stretched beyond its elastic limit, it undergoes plastic deformation. B. Hooke's Law In the 17th century, a scientist named Robert Hooke studied springs and discovered a simple relationship.
Hooke's Law states that, provided the elastic limit is not exceeded, the force (F) applied to an elastic material is directly proportional to the extension (e) it produces.
In simple terms: The more you pull on a spring, the more it stretches, in a predictable way.
Mathematically, we can write this as: `F ∝ e` (F is directly proportional to e)