Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• State Hooke's Law and its formula.
• Understand the relationship between force and extension.
• Interpret a force-extension graph.
• Identify the elastic limit, yield point, and proportional limit.
• Apply Hooke's Law to solve problems.

Lesson summary

This lesson explores the elastic properties of materials, a fundamental concept in the study of Matter. We will investigate how materials like springs and rubber bands behave when they are stretched or compressed. Understanding this is crucial because we see it in action all around us in Ghana – from the shock absorbers in a tro-tro navigating a bumpy road in Accra, to the spring balance used to weigh yams at Kejetia market, to the stretched threads on a Kente loom in the Ashanti Region. By the end of this lesson, you will not only understand the theory but also be able to prove it with a simple experiment and a graph.

Lesson notes

A. Elasticity and Deformation

When you apply a force to an object, you can change its shape or size. This change is called deformation. Elasticity is the ability of a material to resist a deforming influence and to return to its original size and shape when that influence or force is removed. Materials that show this property are called elastic materials. Examples: a spring, a rubber band, a steel ruler. Plasticity is the opposite. A material is plastic if it does not return to its original shape after the deforming force is removed. It is permanently deformed. Example: clay, putty. B. Hooke's Law

In the 17th century, a scientist named Robert Hooke studied the behaviour of springs and other elastic materials. He discovered a very important relationship which we now call Hooke's Law.

Statement of Hooke's Law: > *Provided the elastic limit is not exceeded, the force applied to an elastic material is directly proportional to the extension produced by the force.*

Evaluation guide

• State Hooke's law.
• Project – based learn ing:
•  Guide learners to perform an experiment to demonstrate the relationship between load and
• extension using the spring.