Waves in Motion
A guitar string vibrates up and down. Is this transverse or longitudinal? Why?
Transverse. The vibration moves up and down, perpendicular to the direction the wave travels.
A small bird makes a high-pitched sound. What does that tell us about the vibration speed of its vocal cords?
It means the vocal cords are vibrating very quickly (high frequency).
You clap softly and loudly. What part of the sound wave changes?
The amplitude changes. Louder claps have bigger amplitudes.
What is a wavelength? How do we measure it in a sound wave?
The distance between two compressions (or two rarefactions). Measured from one point on a wave to the same point on the next.
You tap two glasses filled with water. One makes a high pitch, the other a low one. What changed?
The water level. Less water = higher pitch because the glass vibrates faster.
You shout in a cave and hear an echo. What kind of wave helped the sound travel to the wall and back? Explain.
Longitudinal wave. Sound travels in compressions and rarefactions through air and bounces back.
Why do thinner guitar strings produce higher-pitched sounds than thicker ones?
Thinner strings vibrate faster, producing higher frequencies and higher pitch.
What does the height of a wave (amplitude) tell you about the sound?
Taller waves (larger amplitude) mean louder sounds.
If the waves are very close together, what does that say about the sound’s frequency and pitch?
It has a high frequency and high pitch.
our friend says louder sounds have higher pitch. Do you agree?
Disagree. Volume and pitch are different—loudness is amplitude, pitch is frequency
A slinky moves side to side when shaken. What wave type does this represent, and how is it similar to a sound wave?
Longitudinal wave. Like sound, it moves back and forth in the same direction as the wave travels.
You blow into a short straw and a long straw. One makes a higher pitch. Why?
The short straw vibrates faster because there's less air inside, so it makes a higher pitch.
A speaker is turned up. What changes in the sound wave? What stays the same?
Amplitude increases (louder), but frequency (pitch) stays the same.
Two waves have the same height, but one has longer wavelengths. Which has a lower pitch? Why?
The one with longer wavelengths has a lower pitch because it vibrates slower (lower frequency
You watch a speaker vibrate slowly and then quickly. How would the pitch and volume change each time?
Slow = low pitch; fast = high pitch. Louder volume = bigger movements (amplitude).
You shake a rope faster. What will happen to the waves?
The waves will be closer together (higher frequency) and more will appear in the same length.
If a drum’s surface is stretched tighter, how will the pitch change?
The pitch becomes higher because tighter surfaces vibrate faster.
You are far from a bell. It sounds soft. Why?
The sound loses energy over distance, and the amplitude becomes smaller.
Imagine a wave with tall, wide hills. What does it tell you about its amplitude and pitch?
High amplitude (loud sound), long wavelength (low pitch).
Why can sound not travel in space, even though light can?
Sound needs a medium (like air) to travel. Space is a vacuum—no molecules to vibrate
How are water waves and sound waves similar and different?
Both carry energy, but water waves are transverse and need water, while sound waves are longitudinal and need air (or any matter).
You hear two sounds—one low, one high. How can your brain tell the difference if both are equally loud?
The brain detects different frequencies—high pitch has fast vibrations, low pitch has slow ones.
If two sounds have the same pitch but different volumes, how are their waves different?
They have the same frequency, but the louder one has taller waves (greater amplitude).
How does changing wavelength affect what we hear, and why does it matter for musical instruments?
Shorter wavelengths = higher pitch; longer = lower pitch. Musicians adjust instruments to control pitch this way.
You want to build a musical instrument that creates different pitches. What will you change?
You would change the size, length, or tightness of parts (like strings) to affect vibration speed.