Module 12: Waves and Sound
Introduction
Vibrations and waves are all around us. A vibration is just a wiggle in time. A wiggle in both space and time is wave. Sound is an important example of a wave. However, unlike water waves, we cannot see the waving of the sound wave - or can we? In this module we will explore Waves and Sound through 5 lessons.
Learning Objectives
Upon completion of this module, students will be able to:
- Define harmonic motion.
- Solve problems related to simple harmonic motion.
- Display knowledge Hooke's Law and know how to identify the values of its variables
- Explain how waves and vibrations are inter-related.
- Explain the energy associated with a spring, especially the conservation of energy within this system.
- Explain the principle of adding waves.
- Explain the creation of of standing waves.
- Define interference.
- Define superposition in relation to waves.
- Interpret the results of superposing waves.
- Define sound.
- Explain how sound travels in waves.
- Explain the meaning of traveling in a longitudinal wave.
- Explain the Doppler Effect.
- Provide an example of the Doppler Effect.
To Do List
1. Watch the Video Lectures (links below)
2. Complete the Practice Problems (links below)
3. Take the Module 12 Quiz
4. Complete the Exam Practice Problems for Module 12
Lessons
Lesson 12.1 Springs
Hooke's Law, the basic law concerning the vibrations of a spring, is introduced. The mathematics of simple harmonic motion and how waves and vibrations are inter-related are explored.
- Video: Introduction to Springs: Hooke's Law Links to an external site.
- Video: Spring Vibrations Links to an external site.
- Video: Relating Springs to Waves: Simple Harmonic Motion Links to an external site.
- Demonstration: Vertical Simple Harmonic Motion Links to an external site.
- Demonstration: Applying Simple Harmonic Motion to Measure the Acceleration Due to Gravity Links to an external site.
- Video: Resonant Frequencies Links to an external site.
- Practice Problems Download Practice Problems
- Written Solutions Download Written Solutions
- Video Solutions:
- Test Your Understanding!
Lesson 12.2 Energy Stored in Springs
Springs can have energy which is either potential or kinetic - or both. The spring is shown to be a fine example of energy conservation.
- Video: Potential Energy Stored in a Spring Links to an external site.
- Practice Problems Download Practice Problems
- Written Solutions Download Written Solutions
- Video Solutions:
- Test Your Understanding!
Lesson 12.3 Wave Mathematics and Superposition
The proof that something travels in a wave is interference. Various demonstrations are made to show how superposing waves can produce positive and negative interference, and in some cases standing waves.
- Video: Wave Mathematics Links to an external site.
- Video: Standing Waves Links to an external site.
- Demonstration: Mechanical Waves Links to an external site.
- Demonstration: Wave Interference and Superposition: Part 1 Links to an external site.
- Demonstration: Wave Interference and Superposition: Part 2 Links to an external site.
- Practice Problems Download Practice Problems
- Written Solutions Download Written Solutions
- Video Solutions:
- Test Your Understanding!
Lesson 12.4 Sound Waves and Harmonics
Sound is described as a longitudinal wave, and various aspects of superposition of the longitudinal waves are explained.
- Video: Sound Waves Links to an external site.
- Demonstration: Hoag Machine Links to an external site.
- Demonstration: Sound Wave Interference Links to an external site.
- Demonstration: Beat Frequency Bars Links to an external site.
- Demonstration: Hearing Test Links to an external site.
- Demonstration: Visualizing Sound Waves Links to an external site.
- Example: Harmonics: Part 1 Links to an external site.
- Example: Harmonics: Part 2 Links to an external site.
- Practice Problems Download Practice Problems
- Written Solutions Download Written Solutions
- Video Solutions:
- Question 1 solution video contained errors and has been removed
- Question 2 Links to an external site.
- Test Your Understanding!
Lesson 12.5 The Doppler Effect
This lesson concentrates on the Doppler effect, that changes the pitch that sound are perceived to have if they are moving.
- Video: What is the Doppler Effect? Links to an external site.
- Demonstration: Doppler Crank Links to an external site.
- Example: Calculating Frequency Change Due to Moving Sound Source Links to an external site.
- Practice Problems Download Practice Problems
- Written Solutions Download Written Solutions
- Video Solutions:
- Test Your Understanding!
Quiz
Once you have watched the lectures and completed the practice problems, you should demonstrate your understanding by taking the Module 12 Quiz. Be sure to submit the quiz before its deadline.
Coming Up
In the next Module we will learn about Electrostatics.