Lesson Plan

• Describe the relationship between centripetal acceleration and gravitational field strength.
• Derive the orbital speed of a satellite by equating centripetal force to gravitational force.
• Apply the formulas for $a_c$ and $g$ to solve problems involving circular motion and orbital motion.
• Analyse common misconceptions about centripetal force and gravitational fields.

• Projector and screen
• Whiteboard and markers
• Student worksheets with practice questions
• Scientific calculators
• Laptop with internet access for simulation videos
• Rulers/compasses for sketching diagrams

Imagine a satellite gliding silently around Earth—what invisible force keeps it in orbit? Students should recall the formulas $a_c = v^2/r$ and $g = GM/r^2$ from previous lessons. By the end of the lesson they will be able to explain why $a_c = g$ for a circular orbit and calculate orbital speeds.

1. Do‑Now (5'): Quick recall worksheet on $a_c = v^2/r$ and $g = GM/r^2$.
2. Direct Instruction (10'): Derive the equivalence $a_c = g$ for a circular orbit, showing the algebra on the board.
3. Guided Practice (12'): Paired work through the example of a satellite 300 km above Earth, calculating orbital speed.
4. Interactive Simulation (8'): Use an online orbital‑mechanics simulation to visualise centripetal vs gravitational forces.
5. Misconception Check (5'): Clicker questions and class discussion of common errors.
6. Independent Practice (5'): Students solve three practice problems from the notes.

We reviewed how centripetal acceleration and gravitational field strength are mathematically identical for objects in circular orbit. For the exit ticket, each student writes one sentence describing the condition for orbital motion on a sticky note. Homework: complete the worksheet on orbital speed and bring answers to the next class.