Lesson Plan

• Describe how resistive forces affect motion and lead to terminal velocity.
• Derive the expressions for terminal velocity for linear and quadratic drag.
• Calculate terminal velocity for given masses and drag coefficients.
• Explain why acceleration is zero when terminal speed is reached.
• Apply momentum concepts to analyze falling objects experiencing drag.

• Projector and screen
• Whiteboard and markers
• Printed worksheet with example problem
• Graphing calculators
• Short video of a sky‑diver/falling objects

Begin by asking students how a sky‑diver feels when they stop accelerating. Review Newton’s three laws to connect prior knowledge. Explain that today they will discover why objects reach a constant speed when resistive forces balance weight, and they will be able to predict that speed.

1. Do‑now (5'): Quick quiz on Newton’s laws (paper).
2. Mini‑lecture (10'): Recap Newton’s laws, introduce resistive forces, show diagram of forces on a falling object.
3. Derivation activity (12'): Guided derivation of terminal velocity for linear drag, then extend to quadratic drag.
4. Guided practice (10'): Pair work solving the worksheet example (steel sphere), teacher circulates.
5. Concept check (5'): Think‑pair‑share answering why acceleration is zero at terminal speed.
6. Extension (8'): Discuss real‑world examples (sky‑diving, raindrops) and the role of Reynolds number.
7. Summary (5'): Consolidate key equations on board; students copy into notes.

Summarise that terminal velocity occurs when weight equals the resistive force, leaving acceleration at zero while motion continues. For exit, students write the condition “mg = Fₙₑₜ” on a sticky note. Assign homework: complete additional problems on terminal speed for both linear and quadratic drag.