Wave Anatomy
the crest
A light ray hits a mirror and bounces back
Reflection
A wave has a frequency of 2 Hz and a wavelength of 3 m. What is its wave speed?
v=6m/s
A pendulum and a spring both produce the same shape when their position is graphed over time. What shape is it?
A wave!
Sound travels faster in water than in air. In one word, what is the medium doing differently
Water is more dense than air. The spacing between the molecules is tighter and therefore takes less time to transmit the energy between the molecules.
What is the term for the distance between two consecutive crests in a transverse wave?
the wavelength
A pencil looks bent in a glass of water
A wave travels at 6 m/s with a wavelength of 2 m. What is its frequency?
You shorten the string on a pendulum. What happens to the frequency of its swing
Shorter string results in shorter period. Since period is inverse of frequency, the frequency will increase.
Of gas, liquid, and solid, through which does sound travel fastest and why in one sentence
Solid travels fastest
It is the most densely packed medium and the space between them is the shortest distance.
In a longitudinal wave, what is the region called where particles are spread apart and pressure is lower than normal?
Rarefaction
Two waves meet and momentarily cancel each other out.
Describe what the two waves must have in common for this to happen.
Destructive Interference
Same amplitude and opposite phase(inverses of each other)
Frequency doubles but the medium stays the same. What happens to wavelength and what happens to wave speed?
the wavelength will be reduced by 1/3 the speed will remain the same!
A student graphs a heavy mass on a spring and a light mass on the same spring. The shape of both curves is a sine wave. What changed between them and what stayed exactly the same?
the only thing that changes between the two is period of oscillation
we can see this as a change in frequency
the shape of the curve does not change!
Two students are communicating — one pair in air, one pair underwater across the same distance. Whose message arrives first and what principle explains it?
the message in water will arrive first
the speed of sound in water is greater than air since the space between the molecules is less than that in air.
A transverse wave and a longitudinal wave are traveling through the same medium. What is the fundamental difference between them?
*How does the energy travel in each one?
In a transverse wave the particles move perpendicular to the wave's direction — up and down while the wave moves forward. In a longitudinal wave the particles move parallel to the wave's direction — back and forth in the same direction the wave is traveling.
A bat sends out a sound pulse and detects it returning. Name both wave interactions that made this possible
Doppler to detect the change in frequency.
A student increases the frequency of a wave on a string. The wave speed does not change. Using v=λf, explain what must happen to wavelength and why the speed was unaffected.
since frequency and wavelength are inversely related there will be no net change. As one goes up the other goes down and vise versa.
Speed is directly determined by the density of the medium.
In the hallway activity, students standing closer together passed the note faster. What does the spacing between students represent and what real-world phenomenon does the activity model?
the model of the students represents the spacing of molecules.
The less the space the faster the wave travel, the more dense the medium.
A wave's amplitude doubles but its frequency stays the same. What changed, what stayed the same, and what does that tell you about the relationship between amplitude and frequency?
There is no relationship between amplitude and frequency.
the change in frequency will change the wavelength but nothing else.
Noise-canceling headphones never achieve complete silence. Using what you know about destructive interference, explain why perfect cancellation is nearly impossible in the real world.
complete destructive interference can only happen when there is a drone like sound with a constant frequency that can be replicated easily as the "anti-noise" wave from the headphones.
normal human speech is too complex and varying in frequency to achieve full complete destructive interference.
Light from a satellite reaches your eyes through the vacuum of space. Sound from an explosion in space reaches no one. Using what you know about mechanical versus electromagnetic waves, explain why these two outcomes are different.
Light can travel without a medium
Sound requires a medium to travel through, there is no medium in space.