Lesson 1: Types of Forces: Contact vs Non-Contact & Free-Body Diagrams
Exploring forces, net force calculations, motion graphs, energy, and real-world NZ physics applications.
🎯 Ngā Whāinga Akoranga | Learning Intentions
The difference between contact forces (friction, support, tension, drag) and non-contact forces (gravity/weight, magnetic, electrostatic), force units (Newtons N), and free-body force arrow diagrams.
Identify all forces acting on everyday stationary and moving objects, draw free-body diagrams with proportional force arrows, and measure forces using spring balances.
🎥 Media Anchor & Pedagogical Scaffold
Introduction to Forces & Free-Body Diagrams
Video Clip: Contact and non-contact forces — types, examples, and force arrows (Runtime: 3m 40s).
🧠 1. Before Viewing (Activate & Predict)
What invisibly holds us to the Earth, and what stops us from falling through the floor?
👁️ 2. During Viewing (Watch With a Job)
- List: write down TWO contact forces and TWO non-contact forces from the video. Give a real-world example of each.
- Sketch: draw a simple free-body diagram for a book resting on a table — label every force with its name and direction.
- Note: what does the video say about the SIZE of force arrows, and why does that matter when forces are balanced?
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Use spring balances to weigh classroom objects in Newtons (N) and demonstrate support force pushing back up.
Immediate Task: Complete Worksheet 1: Free-Body Force Diagram Practice & Spring Balance Lab Log.
⚡ Whakaoho | Do Now: How Many Forces Act on a Book Sitting Still?
A book rests on the bench. Nothing is moving. Two minutes: write down how many forces are acting on it, then draw them.
Most people say one. Compare with the person beside you — if your numbers differ, one of you is missing a force that is definitely there, and it is the same one nearly everybody misses.
📖 Activity 1: Hunt the Forces, Then Draw Them to Scale
Find them all (13 min). Five stations: a book on a bench, a hanging bag, a box being dragged, a magnet near a paperclip, a ball mid-fall. At each, list every force acting and label it contact or non-contact.
Draw them properly (12 min). Redraw each as a free-body diagram where the arrow length matches the size of the force, not just its direction. Use the spring balance to get real newton readings for the two you can actually measure. An arrow of the wrong length is a wrong answer even when it points the right way.
📝 Activity 2: Year 10 Physics Worksheet & Explanation Scaffolding (20 mins)
Logbook Section 1. Record: (1) your five free-body diagrams with every force named and classified contact or non-contact; (2) two spring-balance readings in newtons, stating exactly what you measured; (3) one object where you and your partner disagreed about a force, and how you settled it.
🏫 Kaiako Planning & Pedagogy Notes
Year 10 Curriculum Alignment: NZ Curriculum Phase 4 Science — Physical World strand. Builds foundational physics problem-solving skills for NCEA Level 1 Mechanics and Level 2 Physics.