Physics (9-1) - 0972 CIE

Sound Continued

Overview

Thunder rolls in seconds after the lightning flash, a shout returns as an echo from a cliff, and an unborn baby is imaged with sound too high-pitched to hear. Sound is a wave that travels through matter, and by timing it, reflecting it and pushing its frequency above hearing we can measure distances, find flaws and see inside the body.

In this lesson you will measure the speed of sound in air from a distance and a time, describe how amplitude and frequency set the loudness and pitch of a note, define an echo and ultrasound, and use ultrasound in sonar and scanning, including calculating depth or distance from the travel time and the wave speed.

Objectives

  1. Describe a method involving a measurement of distance and time for determining the speed of sound in air
  2. Describe how changes in amplitude and frequency affect the loudness and pitch of sound waves
  3. Describe an echo as the reflection of sound waves
  4. Define ultrasound as sound with a frequency higher than 20 kHz
  5. [Supplement] Describe the uses of ultrasound in non- destructive testing of materials, medical scanning of soft tissue and sonar including calculation of depth or distance from time and wave speed

Lesson Note

Sonar maps the seabed, ultrasound scans check unborn babies safely, and engineers find hidden cracks in metal without cutting it open. All rely on the same simple physics of sound waves reflecting and travelling at a known speed. Exam questions here mix short definitions with a speed-distance-time calculation using \(v = d/t\).

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Lesson Evaluation

Congratulations on completing the lesson on Sound Continued. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. The approximate speed of sound in air is A. 3 m/s B. 34 m/s C. 340 m/s D. 3 x 10^8 m/s Answer: C
  2. Increasing the amplitude of a sound wave increases its A. pitch B. frequency C. loudness D. speed Answer: C
  3. Ultrasound is defined as sound with a frequency higher than A. 20 Hz B. 200 Hz C. 2 kHz D. 20 kHz Answer: D
  4. An echo returns from a wall 1.0 s after a clap. The wall is 170 m away. The speed of sound is A. 85 m/s B. 170 m/s C. 340 m/s D. 680 m/s Answer: C
  5. A sonar pulse takes 0.4 s to return from the seabed (speed 1500 m/s). The depth is A. 150 m B. 300 m C. 600 m D. 1200 m Answer: B

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
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Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

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