Mechanical Waves and Sound Flashcards
What is a transverse wave
A wave where particle motion is perpendicular to the direction of energy.
How would a student move the coils of a slinky spring to create a transverse wave?
The student would move the coils side to side so the coils move at a right angle to the movement of the wave energy.
What is a wave crest?
The highest point on a transverse wave
What is a wave trough?
The lowest point on a transverse wave
What is the amplitude of the wave?
The vertical distance from the rest position to a crest or to a trough?
How is the wavelength of a transverse wave determined?
It is the horizontal distance from one crest to the next crest.
What is a longitudinal or compression wave?
A wave where the particle motion is parallel to the direction of energy travel.
What are the names of the low and high points of a longitudinal wave?
Rarefactions and compressions
How would a student move the coils of a slinky spring to create a compression wave?
The student would push then pull the coils in the same direction as the wave energy travels.
How is the speed of a wave determined?
The distance traveled divided by the time of travel.
A student shakes a rope, producing waves with low frequency. If the student increases the frequency of the waves, what happens to their speed?
Speed does not change if the waves are in the same medium.
What is the frequency of a wave?
The number of pulses that pass a given point in a given time interval.
A student shakes a rope, producing a wave with a low frequency. If the student changes to a high frequency, how will the wavelength of the waves change?
The wavelength would be shorter with the higher frequency waves.
What is the relationship between frequency, wavelength and speed?
speed = frequency X wavelength
What is wave interference?
When two waves are in the same place at the same time (overlap), they add together.
What happens to waves after they interfere with each other?
They will return to their original characteristics.
What is constructive interference?
When the crests of two waves and the troughs of two waves align, the amplitude of the combined wave is larger.
What is destructive interference?
When the crest of one wave and the trough of another wave align, the amplitude of the combined wave is smaller.
What is reflection?
Behavior of a wave at a boundary where the incoming wave will bounce back into the original medium.
What is the Law of Reflection?
The angle of the incident wave equals the angle of the reflected wave when measured from the normal.
A student creates a wave pulse in a ripple tank. What will happen to the wave when it strikes a boundary created by the edge of the tank?
The wave will reflect off the tank, and the reflected wave will be inverted.
What is refraction?
When an incident wave enters a new substance at an angle, the transmitted wave will change its speed and bend.
Why does a wave that enters a new medium at an angle bend (refract)?
The wave speed changes, which changes the direction of the wave as different parts of the wave enter the new medium at different times.
What is diffraction?
The bending of a wave around an obstacle or when it passes through a small opening.
A student creates a wave pulse in a ripple tank. What will the student observe when the pulse meets and moves around an obstacle?
The student will observe that some of the wave will reflect off the obstacle, and other parts of the wave will spread out as it moves around the obstacle.
How does the speed of sound depend on the state of matter?
The speed of sound is fastest in a solid and slowest in a gas.
A student sends a pulse in a ripple tank towards a boundary with a narrow slit. What will the student observe if he makes the slit smaller?
The wave will bend more after entering through the slit.
What is resonance?
When an object has a natural frequency of vibration and some force acts on it with the same frequency.
What are some examples of resonance?
Pushing a child on a swing, an opera singer shattering a glass, and the fall of the Tacoma Narrow’s bridge.
What is a sonic boom?
When the air particles move faster than the speed of sound, then a loud noise is produced? (Same as the crack of a whip)
What is the doppler effect?
The apparent change in the frequency of a sound when the source and/or the observer are moving relative to each other.
Sound is an example of what type of wave?
Sound is a longitudinal mechanical wave.
Can sound travel in a vacuum?
No. Sound needs a medium to travel through.
Which characteristic of a wave does pitch represent?
frequency
Which characteristic of a wave does loudness represent?
Amplitude
