Year 9 Science · Unit 4 · Lesson 20
Challenge Worksheet
Learning Goals
Compare three waves
Complete the mega-table by filling in every empty cell. Use your knowledge from across Unit 4.
| Property | Sound wave | Visible light | Seismic P-wave |
|---|---|---|---|
| Wave type (T = transverse, L = longitudinal, EM = electromagnetic) | |||
| Needs a medium to travel? (yes / no) | |||
| Approximate speed in air | |||
| Typical frequency range | |||
| Typical wavelength range | |||
| One practical use in Australia |
Find the mistake
A student's unit summary essay contains five errors
"In Unit 4 I learned that (1) light is a longitudinal wave that needs air to travel through space. I also found out that (2) frequency is measured from the crest of one wave to the trough of the next. In motion, (3) displacement is a scalar quantity because it has a magnitude (size). When reading graphs, I know that (4) the gradient of a speed–time graph gives the distance travelled. Finally, Newton's Laws taught me that (5) balanced forces always mean the object is stationary."
For each numbered error: identify the mistake, write the correct statement, and explain why the incorrect idea is a common misconception.
Error 1 (light as a longitudinal wave needing air)
Error 2 (frequency measured crest to trough)
Error 3 (displacement as a scalar)
Error 4 (gradient of speed–time graph = distance)
Error 5 (balanced forces always mean stationary)
Wrap Up
What is the most important concept you learned in Unit 4 about waves or motion, and how does it connect to everyday life in Australia?