Physics and Math - Waves and Sounds

MCAT Chapter 7

Sinusoidial Waves

individual particles oscillate back and forth with a displacement that follows a sinusoidal pattern

Transverse Wave

Direction of particle oscillation is perpindicular to propagation of the wave

Longitudinal wave

Particles of wave oscillate parallel to direction propigation, oscilating in direction of energy transfer

Wavelength

distance from one crest of wave to the next

frequency

number wavelengths passing fixed point per second

displacement

how far a particular point one wave from equilibrium position

amplitude

maximum magnitude of displacement in a wave

Principle of superposition

when waves interact with eachother, the displacement of the resultant wave at any point is the sum of displacement of the two interacting waves

Constructive Interferance

Waves perfectly in phase the displacements always add together and the amplitude of resultant is equal to sum of the amplitudes of the two waves

Destructive interference

when waves perfectly out of phase, displacements counteract each other and amplitude of resultant wave is difference between amplitude of interacting wave

Partially constructive/destructive

Waves not perfectly in or out of phase with eachother

Traveling waves

Continously shifting points max and min displacement

Standing waves

produced by the constructive and desctructive interference of two waves of same frequency traveling in opposite directions in same space

Antinodes

points of maximum oscillation

Nodes

points where there is no oscillation

Resonance

Increase in amplitude occurs when periodic force is applied at the natural frequency of an object

Damping

decrease in amplitude caused by an applied or nonconservative force

Sound

longitudinal wave transmitted by oscillation of particles in a deformed medium

Pitch

our perception of the frequency of sound

Infrasonic waves

frequencies below 20Hz

Ultrasonic wavees

frequencies above 20,000 Hz

Doppler effect

difference between the actual frequency of a sound adn its percieved frequency when source of soudn and sound is detector moving relative to one another

Echolation

animal emitting sound serves as both the source and detector of sound

Intensity

Average rate of energy transfer per area across a surface perpindicular to wave

Closed boundaries

do not allow oscillation and correspond to nodes

Open boundaries

allow maximal oscillation and correspond to antinodes