Physics quiz 2 Flashcards
What is a wave?
A wave is a regular pattern of motion created by a vibratory disturbance. It can move through matter and some waves move through a vacuum.
Movement of a wave?
Most waves travel through a medium. When it travels through a medium, it causes particles in that substance to oscillate.
What is a medium?
A medium is a gas, liquid or solid substance.
What is oscillation?
Oscillation is a repeating and regular motion (back-and-forth)
What is the equilibrium?
The equilibrium is the rest position. After a wave passes, particles return to the equilibrium.
What are periodic waves?
Periodic waves move at a constant speed and oscillate regularly.
Do waves transfer energy or matter?
A wave transfers energy as it moves from one place to another
What is amplitude?
Amplitude is the height of a wave. It is the maximum displacement of a wave from its rest position/equilibrium. (For M waves - energy of the wave)
What is frequency
Number of wave cycles in one second (measured in Hertz) - pitch
What is a wavelength?
Wavelength is the length of one wave cycle.
What is a transverse wave?
The particles of the medium move perpendicular to the direction of the movement of the wave. For example) a when a person disturbs/shakes a rope. Light is a transverse wave.
What is a longitudinal wave?
Particles of the medium move in the same direction as the movement of the wave. Particles oscillate parallel to the direction of the wave. Sound is a longitudinal wave.
How is sound produced?
Mechanical movement can cause an object to vibrate. A vibrating object causes particles around it, including particles in the air, to vibrate. Vibrating air particles create waves that can be heard.
Why do sound waves require a medium?
Sound waves travel as longitudinal waves and require a medium to pass through. This is because the molecules in a medium carry the sound waves. Sound can’t travel through a vacuum because the vacuum has no molecules which it can vibrate and carry the sound waves.
Characteristics of a sound wave: Rarefaction
Rarefaction is when the particles stop colliding, and spread apart. This produces an area where particles are well separated.
Characteristics of a sound wave: Compression
Compression are when the particles are pressed together.
Characteristics of a sound wave: Pitch
Pitch is the frequency of the wave, it determines the “highness” or “lowness” of a sound. Measured in Hertz.
Characteristics of a sound wave: Loudness/volume
Loudness/Volume is the amplitude of the wave. Measured in decibels (dB)
How does the speed of sound change with different mediums?
The speed of sound increases as the density of the medium increases. This is because sound is a mechanical wave. Mechanical waves rely on the collision of particles in the medium to propagate. When particles are packed together closely, the wave can move faster.
Wave equation?
velocity/speed = wavelength * frequency
Formula for speed?
Speed = d/t, Distance = s*t, Time = d/s
How do echoes occur?
When sound bounces off a flat and hard surface, it can reflect back to the source of the sound. The reflected noise, an echo, sounds exactly like the sound produced originally.
Common applications of sound waves?
Ultrasound:
- bats use to hunt and navigate
- whales/dolphins use to hunt and navigate
- sonography: a probe is pressed against the skin (emits ultrasound waves) then the ultrasound reflects off different types of tissues in the body, the reflected waves are picked up by the probe
