Year 9 Science · Unit 4 · Lesson 2
Challenge Worksheet
Learning Goals
Order the steps
Number the events from 1 to 7 to show the correct order of how a longitudinal sound wave travels from a speaker to your ear. Event 1 = what happens first.
| Order | Event |
|---|---|
| Rarefaction (lower-pressure region) follows as the cone moves back inward. | |
| The eardrum vibrates back and forth in response to the arriving compressions and rarefactions. | |
| The alternating pattern of compressions and rarefactions travels outward through the air at ~340 m/s. | |
| The brain interprets the eardrum vibrations as sound. | |
| The speaker cone moves outward, pushing air molecules together and forming a compression (high-pressure region). | |
| The electrical signal in the speaker causes the cone to vibrate back and forth. | |
| The pattern of compressions and rarefactions reaches the outer ear. |
Find the mistake
A student wrote this answer
"In a transverse wave, the particles move in the same direction as the wave is travelling. When you shake a rope and a wave moves along it horizontally, the rope particles also move horizontally from one end to the other. This is why a surfer at Bondi Beach gets pushed toward the shore by a water wave — the water molecules carry the surfer forward."
1. Identify the specific scientific mistakes in the student's answer. There are at least two errors.
2. Write a corrected version of the student's paragraph. Use the rope wave as your analogy and describe the actual direction of particle motion in a transverse wave.
3. A surfer IS pushed toward shore by a wave. If water molecules don't travel with the wave, how does the surfer actually move toward the beach? Explain using your knowledge of wave energy transfer.
Wrap Up
In one sentence, what was the main idea of this lesson?