Year 9 Science · Unit 4 · Lesson 12
Apply Worksheet
Learning Goals
Order the steps
Number the steps from 1 to 6 to show the correct procedure for calculating average speed over a multi-stage journey. Write 1 next to the first step.
| Order | Step |
|---|---|
| Check your answer for reasonableness — is the speed in the right range for this type of journey? | |
| Apply the formula: average speed = total distance ÷ total time | |
| If the answer is in km/h but you need m/s (or vice versa), convert using ÷ 3.6 or × 3.6 | |
| Add up the distances for all stages to get total distance | |
| Identify the distance and time for each stage of the journey (including any rest stops) | |
| Add up the time for all stages (including rest stops) to get total time |
Real-world context
A cyclist rides from Sydney to Wollongong (90 km total) in three stages. Stage 1: 40 km in 80 minutes. Stage 2: a rest stop of 20 minutes (0 km). Stage 3: the final 20 km in 40 minutes. The remaining 30 km in the middle was covered in the time between Stage 1 ending and Stage 3 beginning — but no time data was recorded for that segment.
Note: For (c), use only the stages where you have both distance and time data, plus the rest stop time.
(a) Calculate the average speed for Stage 1 (40 km in 80 minutes). Give your answer in km/h. Show all working.
(b) Calculate the average speed for Stage 3 (20 km in 40 minutes). Give your answer in km/h. Show all working.
(c) Using the data for Stage 1 (80 min), rest stop (20 min), and Stage 3 (40 min), calculate the average speed for just these three segments: 60 km covered in 140 minutes total. Show working and convert your final answer to m/s.
Wrap Up
In one sentence, what was the main idea of this lesson?