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S2 Science: Sound Waves and Hearing (Paper 3 (challenge))
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Tutor Prep Guide · Sound as a longitudinal wave needing a medium, frequency and amplitude, comparing speeds, echo ranging and uses of ultrasound
S2 Science: Sound Waves and Hearing (Paper 3 (challenge))
This paper deals with ultrasound ranging, sonar, the speed of sound in steel and the path through the ear, and compares media.
Direct answers Ultrasound resolves fine detail because its wavelength is short, and sound is fastest in solids and slowest in gases.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S2 Science: Sound Waves and Hearing |
| Level | S2 |
02 Questions (10 items)
- FoundationA depth sounder sends an ultrasound pulse and receives the echo after 0.06 s. How deep is the water?
- FoundationA sonar pulse returns after 1.2 s and sound travels at 1500 m/s in sea water. How deep is the sea bed?
- FoundationA tap is made on a steel rail where sound travels at 5000 m/s. How far does it travel in 0.002 s?
- IntermediateWhat is the wavelength in air of a 20 000 Hz sound?
- IntermediateA person at the far end of a long steel pipe hears two sounds from one tap. Why?
- IntermediateA sound goes from 30 dB to 50 dB. How many times larger is the intensity?
- ChallengeWhich three main parts does a sound wave pass through in the ear?
- ChallengeHow do bats avoid obstacles in the dark?
- ChallengeHalls have soft board on the walls to reduce echoes. Why does this work?
- Error redoA student mixes up ultrasound and infrasound. What is the correct difference?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 45 m | The round trip is 1500 times 0.06 which is 90 m, so the depth is 45 m. |
| 2 | 900 m | The round trip is 1500 times 1.2 which is 1800 m, and half of that is 900 m. |
| 3 | 10 m | 5000 times 0.002 gives 10 m, showing how much faster sound moves in steel. |
| 4 | About 0.017 m, that is 1.7 cm | Wavelength is 340 divided by 20 000 which gives 0.017 m. |
| 5 | Sound travels faster in steel than in air, so the steel borne sound arrives first | The two media carry sound at different speeds, so the arrivals are separated in time. |
| 6 | One hundred times | A gap of 20 dB is ten squared, which is one hundred times the intensity. |
| 7 | The eardrum, the ossicles and the cochlea | The eardrum vibrates, the ossicles amplify, and the cochlea turns vibration into nerve signals. |
| 8 | They emit ultrasound and listen for echoes, which is echolocation | Ultrasound has a short wavelength, so small objects can be detected. |
| 9 | Soft board absorbs part of the sound energy so less is reflected | Hard surfaces reflect strongly, while soft porous materials absorb sound. |
| 10 | Ultrasound is above the 20 000 Hz limit of hearing and infrasound is below 20 Hz | Both lie outside the range of hearing but on opposite sides of it. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
For sound questions ask three things: is the journey one way or a round trip, which medium is used, and is the question about frequency or amplitude.Tutor Registration →
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