Lesson 1: Introduction to Forces — He Aha te Tōpana?
Students explore the concept of force — contact and non-contact — through Team New Zealand's AC75 foiling yacht, traditional Māori tools, and Polynesian waka navigation. Science anchored in Aotearoa.
📎 Learning Intentions | Ngā Whāinga Ako
Know | Mōhio
- That a force is a push or pull acting on an object, measured in Newtons (N), named after Sir Isaac Newton (1643–1727).
- That forces can be contact (friction, tension, normal reaction) or non-contact (gravity, magnetism).
- That unbalanced forces cause a change in motion; balanced forces result in constant velocity (or rest).
- That traditional Māori and Polynesian peoples applied sophisticated force knowledge in tool design and ocean navigation long before Newton formalized the laws.
Demonstrate | Whakaatu
- Draw a labelled free body diagram for a simple object (e.g., a book resting on a table, a waka sailing upwind) showing at least 2 forces with direction arrows.
- Classify 8 given forces as contact or non-contact.
- Explain in 2–3 sentences why Team New Zealand's AC75 can foil (lift above the water) using force concepts.
📐 Curriculum Alignment | Hononga Marautanga
Explore, describe, and represent patterns and trends for everyday examples of physical phenomena, such as motion, forces, electricity, and magnetism.Ministry of Education (2007). The New Zealand Curriculum, p. 60.
Use their growing scientific knowledge and skills to participate as critical, informed, and responsible citizens in a range of contexts.Ministry of Education (2007). The New Zealand Curriculum, p. 17.
🌿 Whakatūwhera — Cultural Opening
He waka eke noa — he tōpana kotahi.
"A canoe we are all in together — one force." Every waka hourua (double-hulled voyaging canoe) is a masterpiece of applied physics: buoyancy, thrust, drag, and lift all in balance. Polynesian navigators understood these forces intuitively thousands of years before Newton published his laws.
🎤 Kaiako Hook (5 min)
Show the famous Emirates Team New Zealand AC75 foiling video (see below). Ask: "Why does the boat lift out of the water? What forces allow this? Which forces would drive it back down?"
Then connect: "What did Polynesian waka navigators know about water resistance that allowed them to cross Te Moana Nui a Kiwa 3,000 years before Newton?"
🎬 Watch | Mātakitaki
🎬 Kaiako: Select and embed a video here
Suggested search: "introduction to forces physics Year 10 contact non-contact free body diagram"
Search YouTube for a 5–10 min video introducing forces: contact vs non-contact, Newton's definition, and free body diagrams. Suitable for Year 10 (NZC Level 5).
Once you have selected a video, verify it is age-appropriate and plays correctly, then embed it using the iframe pattern in this file. Add data-oembed-verified="true" only after verifying via YouTube oEmbed.
Focus on: contact vs. non-contact forces, the definition of a Newton, and how free body diagrams show multiple forces acting on one object.
📚 Lesson Content
Part 1: What Is a Force? (10 min)
🔑 Force Definition
A force is a push or pull that acts on an object.
- Unit: Newton (N) — 1 N ≈ the weight of a 100 g apple.
- Direction matters: Forces are vectors — they have both magnitude and direction.
- Multiple forces can act at once — the net (total) force determines what happens.
| Force Type | Contact? | NZ Example | Te Reo Māori |
|---|---|---|---|
| Gravity (Weight) | Non-contact | Apple falling at Pipitea Market | Urutā |
| Normal Reaction | Contact | Marae floor pushing up on your feet | Tūāhua |
| Friction | Contact | Waka paddle gripping water | Āuahi |
| Tension | Contact | Halyards on a Laser dinghy | Ōwheo |
| Drag | Contact | Air resistance on an AC75 hull | Tō huri |
| Lift | Contact | Hydrodynamic lift on AC75 foils | Ara ake |
| Thrust | Contact | Rocket Lab Electron engine | Tōpana |
| Magnetism | Non-contact | MRI scanner at Auckland Hospital | Autō |
Part 2: Free Body Diagrams (15 min)
A free body diagram (FBD) is a simple drawing that shows all forces acting on an object as labelled arrows. The length of each arrow represents the size of the force; direction shows which way it acts.
Rules for FBDs:
- Draw the object as a simple box or dot.
- Draw arrows starting FROM the object's centre, pointing in the direction of each force.
- Label every arrow with the force name and magnitude (in N) if known.
- If forces are balanced, arrow lengths should match on opposite sides.
Practice: Draw FBDs for: (a) a rugby ball in the air, (b) a kiwi standing on a branch, (c) Team New Zealand's AC75 foiling at full speed.
Part 3: Māori Tool Demo — Whētuki (10 min)
A whētuki is a traditional Māori lever tool used to pry open shellfish and move heavy stones during pā construction. Ask: Where is the pivot (fulcrum)? Where is the effort force applied? Where is the load force?"
This is force multiplication — a small input force (effort) over a long arm creates a large output force at the load. The same principle is used in the AC75's canting keel (a lever that shifts ballast to control heeling force).
Part 4: AC75 Forces Analysis (10 min)
The Emirates Team New Zealand AC75 foiling yacht uses four main forces to fly above water:
- Gravity (downward): The weight of the boat (~7 tonnes) pulling it into the water.
- Lift (upward): Hydrodynamic lift from the T-foils, generated when water flows over the foil shape — identical to how an aeroplane wing works.
- Thrust (forward): Wind force on the rigid wing sail (wingsail), converted to forward motion.
- Drag (backward): Water and air resistance opposing forward motion — reduced by foiling above water.
When Lift > Weight, the boat rises. When Drag < Thrust, the boat accelerates. The engineering challenge: balance all four.
✅ Assessment | Aromatawai
🎟 Exit Ticket (5 min)
- Name two contact forces and two non-contact forces you experienced today.
- Draw a quick free body diagram of a waka paddler's paddle in the water. Label at least 3 forces.
- If the thrust on the AC75 is 15,000 N forward and drag is 12,000 N backward, is the boat accelerating, decelerating, or at constant speed? Explain.
🧑🏫 Kaiako Notes
- Common misconception: Students often think that moving objects need a constant force. Clarify Newton's First Law preview: an object in motion stays in motion unless a net force acts on it.
- Extension: Calculate the weight of the AC75 in Newtons (W = mg, g = 9.8 m/s²). If lift exactly equals weight, what is the lift force in Newtons?
- Support: Provide a pre-drawn FBD with arrows and ask students only to label and identify contact vs. non-contact.