| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand how the concept of gravitational potential leads to the gravitational potential energy of two point masses and use EP = –GMm / r |
Learning Objective/s:
- Describe gravitational potential as the potential‑energy‑per‑unit‑mass and explain why it is negative.
- Derive the expression φ = ‑GM/r for a point mass from the definition of work.
- Apply U = ‑GMm/r to calculate the gravitational potential energy of a two‑mass system.
- Explain how the formula is used in orbital‑mechanics and escape‑velocity problems.
- Solve a quantitative problem (e.g., Earth–Moon system) using the derived equation.
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Materials Needed:
- Projector and screen
- Whiteboard and markers
- Printed worksheet with practice problems
- Scientific calculators
- Formula sheet for gravitational constants
- Diagram of a point mass and test mass (handout or slide)
- Clicker or online quiz tool for concept check
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Introduction:
Begin with a striking question: “What would happen to the energy of a satellite if we moved it farther from Earth?” Connect this to students’ prior knowledge of gravitational force and energy. State that by the end of the lesson they will be able to express that energy using the gravitational potential concept and the formula U = ‑GMm/r.
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Lesson Structure:
- Do‑now (5'): Quick written response on the definition of potential energy per unit mass; teacher reviews answers.
- Mini‑lecture (10'): Derive φ = ‑GM/r using the work‑integral, display the point‑mass diagram, and emphasise the negative sign.
- Guided example (10'): Work through the Earth–Moon calculation step‑by‑step, highlighting substitution of values.
- Collaborative practice (15'): Pairs solve a similar problem (e.g., Sun–Jupiter system) using calculators; teacher circulates for support.
- Concept check (5'): Clicker quiz with three MCQs on sign of potential, reference point at infinity, and dependence on distance.
- Summary & exit ticket (5'): Students write one sentence summarising the relationship between φ and U and answer an exit question on how the formula would change for a uniform sphere.
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Conclusion:
Recap the key steps: defining gravitational potential, deriving the –GM/r expression, and applying it to compute potential energy. Collect exit tickets to gauge understanding and assign a worksheet with two additional two‑mass problems for homework.
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