| Lesson Plan |
| Grade: 12 |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: derive, from the definitions of pressure and density, the equation for hydrostatic pressure ∆p = ρg∆h |
Learning Objective/s:
- Describe the concepts of pressure and density and their units.
- Derive the hydrostatic pressure equation Δp = ρ g Δh from force equilibrium.
- Apply the equation to calculate pressure differences in fluid columns.
- Explain the linear relationship between pressure and depth in an incompressible fluid.
- Analyse real‑world examples such as water depth or manometer readings.
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Materials Needed:
- Projector or interactive whiteboard
- Printed worksheet with derivation steps
- Diagram of a vertical fluid column (handout or slide)
- Calculator for numerical example
- Whiteboard and markers
- Optional: density measurement kit (e.g., water bottle)
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Introduction:
Begin with a quick question: “What units do we use for pressure and why?” Connect this to students’ prior work on force‑area relationships. State that by the end of the lesson they will be able to derive and use the hydrostatic pressure formula, which will be the success criteria.
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Lesson Structure:
- Do‑now (5'): Students write the definition of pressure and give an example.
- Mini‑lecture (10'): Review pressure, density, and the assumptions of an incompressible, static fluid.
- Guided derivation (15'): Using a diagram of a fluid column, students step‑by‑step balance forces to arrive at Δp = ρ g Δh.
- Worked example (10'): Calculate the pressure increase at 5 m depth in water; discuss the result.
- Check for understanding (5'): Exit ticket – write the hydrostatic equation and briefly explain each term.
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Conclusion:
Recap the derivation and emphasise the linear pressure‑depth relationship. Collect exit tickets to gauge mastery, and assign a homework problem requiring students to compute pressure differences for different fluids and depths.
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