Lesson 9: Work, Energy & Power Basics (W = F d)
Exploring forces, net force calculations, motion graphs, energy, and real-world NZ physics applications.
🎯 Ngā Whāinga Akoranga | Learning Intentions
Work done as energy transferred when a force moves an object through a distance (W = F d), measured in Joules (J), gravitational potential energy (E_p = m g h), and kinetic energy (E_k = ½ m v²).
Calculate work done W = F d when lifting or pushing objects, calculate E_p and E_k, and explain conservation of mechanical energy.
🎥 Media Anchor & Pedagogical Scaffold
Work, Energy & Power Fundamentals
Video Clip: Work done and power — W = Fd, P = W/t, and the joule/watt in context (Runtime: 3m 53s).
🧠 1. Before Viewing (Activate & Predict)
If you push as hard as you can against a solid brick wall for an hour but the wall doesn't move, how much mechanical work have you done?
👁️ 2. During Viewing (Watch With a Job)
- Define: what does 'doing work' mean in physics? Is lifting a heavy bag upward 'work' in the physics sense?
- Calculate: a force of 50 N moves an object 3 m. How much work is done? Include units.
- Connect: if two people both do 200 J of work, but one does it in 10 s and the other in 20 s, who has more POWER?
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Have students calculate work done lifting school bags onto desks vs carrying them horizontally.
Immediate Task: Complete Worksheet 9: Work, Potential & Kinetic Energy Calculation Workbook.
⚡ Whakaoho | Do Now: Hold a Heavy Bag Still. How Much Work Have You Done?
Your arms ache after a minute. That feels like work.
Two minutes: in the physics sense, how much work have you done on the bag? Write W = F d, then look at what happens to the answer when d is zero. Physics and everyday language disagree here, and the exam uses the physics one.
📖 Activity 1: Work Done, Then Energy Stored and Released
Calculate work (13 min). Find W = F d for lifting, pushing and dragging tasks. The force has to be in the direction of the movement — if it is not, that part of the force does no work. Answers in joules.
Follow the energy (12 min). Calculate Ep = m g h for an object lifted to a height, then Ek = ½ m v² for the same object at the bottom of the drop. Compare the two numbers. They will be close but not equal — and the size of the gap is the next question worth asking.
📝 Activity 2: Year 10 Physics Worksheet & Explanation Scaffolding (20 mins)
Logbook Section 9. Record: (1) three work calculations with working and units; (2) a matched Ep and Ek pair for one object with the two compared; (3) an explanation of where the missing energy went, written using the word transferred rather than lost.
🏫 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.