Year 9 Science · Unit 4 · Lesson 20
Apply Worksheet
Learning Goals
Odd one out
Circle the item that does not belong in each group. Then write the odd one and a brief reason in the answer column.
| # | Group | Odd one + reason |
|---|---|---|
| 1 | Amplitude Wavelength Frequency Acceleration | |
| 2 | Radio waves Microwaves X-rays Sound waves | |
| 3 | Pitch Loudness Decibel Refraction | |
| 4 | Distance Speed Displacement Velocity | |
| 5 | Newton's First Law Terminal velocity Balanced forces Wavelength |
Real-world synthesis scenario
A professional surfer is towed out to a 10-metre ocean wave breaking at 25 km/h at Nazaré, Portugal — one of the world's most powerful surfing breaks. The surfer has a mass of 75 kg. When the surfer wipes out, they decelerate from 25 km/h to 0 in approximately 3 seconds as the wave pushes them underwater. During the session, the surf crew monitors weather using radio communication and GPS positioning.
(a) Describe the wave properties of the Nazaré ocean wave. In your answer, refer to: amplitude, wave type (transverse or longitudinal), and the direction of energy transfer.
(b) Calculate the net force on the 75 kg surfer decelerating from 25 km/h to 0 in 3 seconds. Hint: convert km/h to m/s first (÷ 3.6). Then use a = Δv ÷ t and F = ma.
(c) Which Newton's Law best describes what happens when the surfer pushes backward on the board and the board pushes them forward? Name the law and explain it in the context of surfing.
(d) Identify the two types of electromagnetic wave used by the surf crew for safety (GPS and radio communication). For each, state one key property that makes it suitable for that use.
Wrap Up
In one sentence, describe how waves and motion concepts are connected in the sport of surfing.