Sound Waves Student Packet
Sonic Science: Sound Waves
Grade 7 Physical Science • Investigation & Practice Packet
Page 1 of 6
Student Name:
Date:
Period:
SECTION 1
What Exactly Is a Sound Wave?
All sound begins with a vibration—a rapid back-and-forth movement of matter. When an object vibrates, it collides with neighboring particles. Sound is a mechanical wave, meaning it requires a medium (solid, liquid, or gas) to travel through. Sound cannot travel across empty space.
Sound waves are longitudinal waves: particles vibrate parallel to the wave's path of motion. This produces repeating regions of high particle density called compressions and regions where particles spread out called rarefactions.
Figure 1.1: Anatomy of a Longitudinal Wave
Particle density and wavelength
Wave Energy Direction Compression (High pressure) Rarefaction (Low pressure) Wavelength (λ)
A Key Concept Vocabulary Match
Match each term to its scientific meaning by writing the corresponding letter.
1. Medium: Matter through which wave travels
2. Compression: High density particle zone
3. Rarefaction: Low density particle zone
4. Mechanical Wave: Wave needing matter
B Checks for Understanding
1. If an alarm clock rings inside a sealed jar from which all air has been vacuumed out, will you hear it? Explain using the concept of a medium.
2. Describe how particles move relative to the direction sound energy moves in a longitudinal wave.
Unit 4: Waves & Energy • Student Investigation Packet Page 1
PAGE 2
Wave Properties: Pitch, Frequency & Volume
Sonic Science Packet
SECTION 2
Frequency and Amplitude: What We Hear
Frequency = Pitch
Frequency is wave cycles per second, measured in Hertz (Hz). Rapid vibrations create high frequency waves with short wavelengths, producing a high pitch (e.g., bird whistle). Slow vibrations produce a low pitch (e.g., bass horn).
Amplitude = Loudness
Amplitude reflects how much energy a wave carries. Higher amplitude compresses particles tighter together. Greater amplitude creates greater volume/loudness, measured in decibels (dB).
Figure 2.1: Oscilloscope Representations of Sound
Comparing Frequency (Pitch) Low Pitch High Pitch
Comparing Amplitude (Volume) Quiet Loud
A Wave Graph Interpretation
Examine the labeled wave representations below and answer the questions.
Wave A Wave B Wave C
Which wave produces the highest pitch? Explain why:
Comparing Wave A and Wave B, which wave is louder? What visual evidence proves this?
Which wave has the longest wavelength?
B Real-World Acoustic Scenarios
Scenario 1: Mosquito vs Bass Drum
A mosquito buzzes at a faint 600 Hz. A concert drum booms loudly at 60 Hz.
Which sound has higher amplitude? Higher frequency?
Scenario 2: The Screaming Referee
A referee blows a whistle softly, then blows it with maximum lung force.
What wave property changed (frequency or amplitude)? Explain:
Unit 4: Waves & Energy • Student Investigation Packet Page 2
PAGE 3
Sound Transmission: Solids, Liquids & Gases
Sonic Science Packet
SECTION 3
How Matter Controls the Speed of Sound
Sound waves require physical collisions between particles to transmit energy. In solids, particles are packed tightly in fixed positions, allowing vibrations to pass almost instantly. In liquids, particles are slightly farther apart and slide past each other, giving moderate speeds. In gases, particles are widely spaced, so sound travels slowest. In a vacuum, there is no matter, meaning sound cannot travel at all!
Figure 3.1: Particle Arrangement & Wave Speed Comparison
1. SOLID ~5,960 m/s (Fastest)
Tightly packed particles
2. LIQUID ~1,500 m/s (Moderate)
Closer, fluid contact
3. GAS ~343 m/s (Slow)
Widely spaced particles
4. VACUUM 0 m/s (No Sound)
Empty Space
No particles present
Table 3.1: Measured Speed of Sound in Common Media (at 20°C)
| Medium | State of Matter | Speed (m/s) | Relative Speed |
|---|
| Steel (Solid metal) | Solid | 5,960 m/s | ~17.4× faster than air |
| Water (Fresh pool) | Liquid | 1,482 m/s | ~4.3× faster than air |
| Air (Dry atmosphere) | Gas | 343 m/s | 1.0× (Baseline) |
| Outer Space (Vacuum) | Vacuum | 0 m/s | No transmission |
A Data Interpretation & Inquiry Questions
1. Based on Table 3.1, approximately how many times faster does sound travel through solid steel than through air?
2. In old western movies, people put an ear flat against a metal rail track to hear a train miles away. Why is this more effective than listening through the air?
3. Explain at the molecular level why sound cannot travel across the vacuum between the Sun and Earth.
Unit 4: Waves & Energy • Student Investigation Packet Page 3
PAGE 4
Hands-On Investigation: Sound Lab Stations
Sonic Science Packet
Lab Objective: Test how vibrational energy travels through different materials and record real-world observations. Work with your station partner to perform the simple setups below.
1
STATION 1: The String Telephone & Conduction (Solids)
Cups, taut string, spoon
Procedure: Stretch the string telephone until the string is completely tight. Have partner whisper a secret word. Next, test with a slack string. Then, tie a spoon to the string, press string ends to ears, and tap the spoon.
Tight String vs Slack String Observation:
Why does tension allow sound to travel better?
2
STATION 2: The Tuning Fork & Water Splash (Liquids)
Tuning fork, bowl of water
Procedure: Strike the rubber mallet against the tuning fork. Listen to it in air. Then, strike it again and gently touch the vibrating prongs to the surface of the water in the bowl.
What happened to the water surface?
What does this prove about mechanical wave energy?
3
STATION 3: The Desk Rapping Test (Solid vs Gas)
Wooden desk, knuckle
Procedure: Sit upright and have your partner tap very lightly on the far end of the wooden desk so you barely hear it through the air. Now, press your ear flat against the wood surface while partner taps with the exact same force.
Describe difference in loudness and clarity:
Connect observation to particle spacing in wood vs air:
Station Debrief Question:
Based on Stations 1, 2, and 3, rank the three states of matter from fastest / most efficient to slowest at transferring sound energy, and cite your primary piece of evidence.
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PAGE 5
Independent Practice: Sound Scenarios & Calculations
Sonic Science Packet
1
Sci-Fi Movie Physics Buster
In a popular sci-fi movie, two spaceships battle in outer space. When one spaceship explodes, the camera zooms outside the spaceship and the audience hears a colossal, room-shaking explosion: "KA-BOOOOM!"
a) Is this scene scientifically accurate? Why or why not?
b) If the astronaut was inside a pressurized cockpit when a tool struck their own ship's hull, would they hear it? Explain:
2
The Whale Song Mystery
Blue whales produce low-frequency vocalizations that travel hundreds of miles through the ocean to communicate with distant pods.
a) Why does the whale's call travel much farther in ocean water than an equally loud animal sound through air on land?
b) If ocean water temperature warms up, water molecules vibrate and move faster. What do you predict happens to the speed of sound?
3
Sound Math: Distance, Speed & Echoes
Core Physics Formula: \(\text{Speed} = \frac{\text{Distance}}{\text{Time}}\) | \(\text{Distance} = \text{Speed} \times \text{Time}\)
Speed in air ≈ 340 m/s
a) Thunder & Lightning: You see a flash of lightning, and exactly 4.0 seconds later you hear the boom of thunder. Assuming sound travels at 340 m/s in air, calculate how far away the lightning struck. (Show your work!)
b) Submarine Sonar Echo: A submarine emits a sonar pulse into seawater (speed = 1,500 m/s). The sound reflects off the ocean floor and the echo returns to the submarine 2.0 seconds later. How deep is the ocean floor? (Hint: The sound traveled down and back!)
Unit 4: Waves & Energy • Student Investigation Packet Page 5
PAGE 6
Mastery Assessment & Scientific Synthesis
Sonic Science Packet
PART 1
Concept Discrimination Questions
Circle the letter of the single best response.
1. Through which medium will sound travel fastest?
A Cold nitrogen gas
B Liquid pool water
C A solid cast iron beam
D The vacuum of deep space
2. An engineer increases the amplitude of a sound. What changes?
A Pitch becomes noticeably higher
B Volume becomes louder
C Wave speed doubles immediately
D Wavelength drops to zero
PART 2
Comparative Matrix: Sound Waves vs Light Waves
Complete the comparison matrix below by filling in each blank cell.
| Feature | Sound Waves | Light Waves |
|---|
| Type of Wave | Longitudinal (Mechanical) | Transverse (Electromagnetic) |
| Requires a Medium? | Yes (Must have matter) | No (Can travel through vacuum) |
| Fastest Medium | | Vacuum / Space (300,000,000 m/s) |
| Blocked / Zero Speed | Vacuum (Cannot travel at all) | |
PART 3
Scientific Reasoning (CER Writing Challenge)
Prompt: At an outdoor concert 300 meters from the stage, a student feels the bass rumble through the wooden bleachers beneath their feet a fraction of a second before they hear the vocal notes through the air. Explain why this happens.
CLAIM: (State your direct scientific answer)
EVIDENCE: (Cite specific facts about speed in wood/solids vs air/gas)
REASONING: (Explain the particle mechanics that cause this speed difference)
Unit 4: Waves & Energy • Student Investigation Packet Page 6
