Lesson 4: Distance-Time Graphs & Gradient Interpretation
Exploring forces, net force calculations, motion graphs, energy, and real-world NZ physics applications.
🎯 Ngā Whāinga Akoranga | Learning Intentions
How distance-time (d-t) graphs represent motion: flat line = stationary, constant slope = constant speed, steep slope = fast speed, curve = acceleration.
Construct d-t graphs from journey data tables, calculate speed from graph gradient (gradient = rise / run = Δd / Δt), and describe multi-stage journeys.
🎥 Media Anchor & Pedagogical Scaffold
Reading & Graphing Distance-Time Motion
Video Clip: Distance-time graphs — reading speed from gradient and identifying motion types (Runtime: 4m 00s).
🧠 1. Before Viewing (Activate & Predict)
What does a horizontal flat line on a distance-time graph tell you about an object's motion?
👁️ 2. During Viewing (Watch With a Job)
- Identify: on a distance-time graph, what does a steep upward line mean compared to a gentle upward line?
- Calculate: a graph shows 60 m covered in 4 seconds. Calculate the speed from the gradient.
- Describe: what does a horizontal line on a distance-time graph tell you about the object's motion?
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Use ultrasound motion sensors connected to projectors to display live d-t graphs of students walking toward and away from the sensor.
Immediate Task: Complete Worksheet 4: Distance-Time Graph Analysis & Gradient Calculation Lab.
⚡ Whakaoho | Do Now: Sketch the Trip to the Dairy
Two minutes, rough axes: sketch a distance-time graph for walking to the dairy, waiting to be served, then running home.
Now check one thing on your sketch. Where the line is flat — does that mean stopped, or does it mean going backwards? That single question catches most of the class, and it is worth being wrong about now rather than in November.
📖 Activity 1: Build the Graph, Then Read Speed From It
Plot from data (13 min). Turn the journey data table into a distance-time graph. Axes labelled with units, a scale that uses most of the page, points plotted before you join anything.
Gradient is speed (12 min). Calculate the gradient of each straight section — rise over run, that is Δd over Δt. That number is the speed for that stage, in m/s. Then describe the whole journey in words using your calculated speeds, including what the flat section means.
📝 Activity 2: Year 10 Physics Worksheet & Explanation Scaffolding (20 mins)
Logbook Section 4. Record: (1) your plotted graph with both axes labelled and units shown; (2) a gradient calculation for every section with the speed it gives; (3) a written description of the journey naming each stage and its speed — the stationary stage included.
🏫 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.