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 the principle of flotation.
• Relate an object's weight to the fluid it displaces.
• Compare how density affects whether an object floats or sinks.
• Apply the principle to solve simple problems.

Lesson summary

Have you ever wondered why a massive cargo ship made of thousands of tonnes of steel can float majestically on the sea at Tema Harbour, but a small pebble you toss into the water sinks immediately? Or why a canoe on the Volta Lake can carry people and goods without sinking? The answer lies in a fundamental principle of physics known as the Principle of Flotation. This lesson builds upon our previous knowledge of Archimedes' Principle to explore the specific conditions that allow an object to float. Understanding this principle is crucial not only for passing exams but also for appreciating the science behind shipbuilding, fishing, and even how certain animals survive in water.

Lesson notes

Recap: Archimedes' Principle Before we dive into flotation, let's remember what we already know. Archimedes' Principle states that:

> *An object wholly or partially immersed in a fluid experiences an upthrust equal to the weight of the fluid displaced.* Fluid: Any substance that can flow (liquids and gases). Upthrust (or Buoyant Force): The upward force exerted by the fluid on the immersed object. It's what makes you feel lighter in a swimming pool. Displaced Fluid: The volume of fluid that is pushed aside by the object.

This upthrust is always present, whether the object floats or sinks. The key to flotation is understanding how this upthrust compares to the object's own weight. The Principle of Flotation The Principle of Flotation is a special case of Archimedes' Principle that applies only to objects that are floating.

> The Principle of Flotation states that a floating object displaces a weight of fluid equal to its own weight.

Evaluation guide

• State principle of flotation.
• Collaborative Learning: Following from the activities in Archimedes' principle, let learners
• compare the weights of substances to their respective fl uids they displace for both floating objects
• and non -floating objects and let learners draw conclusions from that.