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Define: Wave and types
- Wave: transfer of momentum and energy from one point to another
- Types: Mechanical, Electromagnetic, and matter
What are two types of mechanical waves?
Transverse and longitudinal
Define: wavelength, Frequency, period, and amplitude. Give units
- wavelength (lambda): distance between two identical (repeated) points in a wave (meters)
- Frequency (f): the amount of waves that pass a point in space in 1 sec (m/s=Hz)
- Period (T): recipricol of frequency - time/wavelength
- Amplitude (A): Maximum displacement from 0 (always positive)
What are the two big rules for waves?
- 1: the speed of a wave is determined by the medium and type of wave. NOT frequency. Frequency is inversely propoprtional to wavelength in any given medium
- 2:When a wave transfers between mediums, the velocity changes, but the frequency does not
Equation for velocity of a wave.
2 aspects of media that affect the velocity of a wave
- 1: elasticity/resistance to change in shape
- 2:inertia/resistance to change in motion
how do decibels work?
They are a logrithmic representation of sound intensity that create an intuitive scale.
every factor of 10 change in intensity is equivilent to an addition/subraction of 10 decibels. 300 to 3000 is 10 decibels, 10-10000 is 30 decibels
define:phase, constructive and destructive interference
- phase: is kind of an address for a wave. It describes its wavelength, frequency, and place in time against its origin.
- constructive: when 2 or more waves superimpose and the sum of their displacements are larger
- deconstructive: when 2 or more waves superimpose and the sum of their displacements are smaller
Describe simple harmonic motion
Any motion that is repetitious and resembles a sine wave as a function of time
3 properties to be aware of in simple harmonic motion
- 1: Acceleration is directly proportional to displacement, but opposite in sign.
- 2: Acceleration and displacement are related byu the square of the frequency
- 3: energy of a system in simple harmonic motion oscillates between kinetic and potential energy.
Define: doppler effect
because sound waves move at speeds independently of the speed of what created them, the frequency of the wave experienced by a stationary observer changes with the distance it travels and is therefore experienced differently although it is the same wave.
equation for Decibels
Give equation for nodes of standing wave
- L=[n(lambdan)]/4 (n=odd positive integers)
- L=[n(lmabdan)]/2 (n= all positive integers)
what is the equation for beat frequency
fb=|f1 - f2|
Doppler effect equations
- [(delta)f/fs] = v/c
- [(delta)(lambda)/(lambdas) = v/c