Sound Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Sound.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

A longitudinal mechanical wave that travels through a medium (solid, liquid, or gas) via alternating compressions and rarefactions of particles.

Vibrating air that your ears detect. No medium, no sound (space is silent).

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Sound requires a physical medium to propagate — it cannot travel through a vacuum.

Common stuck point: Sound travels faster in solids than in air (molecules are closer together).

Sense of Study hint: When solving a sound problem, first note the medium (air, water, solid) and look up or use the given speed of sound in that medium. Then apply v = f\lambda to relate speed, frequency, and wavelength. For perceived pitch, focus on frequency; for perceived loudness, focus on amplitude.

Worked Examples

Example 1

easy
Thunder is heard 6 \text{ s} after lightning is seen. How far away was the lightning strike? Use the speed of sound v = 340 \text{ m/s}.

Solution

  1. 1
    Light travels almost instantaneously, so the delay is due to the speed of sound.
  2. 2
    Use the distance formula: d = vt.
  3. 3
    d = 340 \times 6 = 2040 \text{ m} \approx 2 \text{ km}

Answer

d \approx 2040 \text{ m} \approx 2 \text{ km}
Sound travels much slower than light. The time delay between seeing lightning and hearing thunder can be used to estimate the distance of the lightning strike.

Example 2

medium
A sound wave in air has a wavelength of 0.5 \text{ m}. What is its frequency? Is this audible? Use v = 340 \text{ m/s}.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A person shouts toward a cliff and hears the echo 4 \text{ s} later. How far is the cliff? Use v = 340 \text{ m/s}.

Example 2

medium
A sonar pulse is sent from a ship and the echo returns 0.8 \text{ s} later. The speed of sound in seawater is 1500 \text{ m/s}. How deep is the ocean floor at that point?
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Background Knowledge

These ideas may be useful before you work through the harder examples.

longitudinal wavefrequencyamplitude