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Gr 11 physics 8.5
8.1-8.5 sans 8.2
Term | Definition |
---|---|
cyclical motion | back and forth motion |
midpoint/equilibrium | cyclical motion that occurs about a point |
Vibration | repeated motion of a particle when displaced from its resting position. source of waves| the cyclical motion of an object about an equilibrium point |
mechanical wave | transfer of energy through a material by particle vibration |
net motion | displacement of a particle over a certain time interval| after a wave passes through a medium, the particles return to their original location. there is no -- of particles when they stop vibrating so their net displacement is 0 |
waves | vibration that travels & carries energy from one point to another |
transverse wave | wave in which the particles vibrate perpendicular to the direction of the flow of energy |
longitudinal wave | wave in which the particles vibrate in the same direction as the energy flow |
geometric wave characteristics | amplitude, wavelength, phase, phase shift |
amplitude | maximum displacement of a vibrating particle in a wave, from the equilibrium point| half the distance between the maximum & minimum values| greater amplitude=greater sound| measure how much energy a wave is transferring |
wavelength | distance between two similar points in successive identical cycles in a wave |
waveform | shape of a wave when graphed |
crest | maximum point of a transverse wave |
trough | minimum point of a transverse wave |
phase | the x of a unique point of a wave. measured in meters. shown as a decimal percentage(halfway through a single cycle is a phase of 0.5(no units)) |
phase shift | two waves can have identical characteristics but shifted along the x-axis. shift of an entire wave with respect to an identical wave along the x-axis |
in phase | their shifts are equal |
out of phase | their shifts are unequal |
frequency(f)(Hz) | number of complete cycles per second of a wave a wave and the vibrating particles that create and sustain the wave have the same -- |
period(T)(s) | time it takes for vibrating particle in a wave to complete one cycle can be found by measuring the length of time it takes for one wavelength to pass a fixed point |
frequency and time relation | T=1/f or f=1/T |
wavespeed(m/s) | v=λ(m)/T(s)=length of one cycle/time for one cycle| measure of how fast the energy in the wave is moving depends on the medium in which its travelling |
simple harmonic motion(SHM) | any motion that repeats itself at regular intervals about an equilibrium point| type of vibration |
universal wave equation | v=λf or v=λ/T |calculate wave speed| speed of wave to its frequency and wavelength. applies to all waves |
factors that affect wave speed | temperature(higher temp = faster particles), linear density(of the medium), tension(of the medium) |
linear density or mass per unit distance | μ=m/L |determines how much force it takes to make vibrate| mass of string(kg)/length of string(m) |
tension | v=√^FT/μ |determines how much energy will be absorbed| √force of tension(N)/linear density(kg/m) |
audible sound waves | range of sensitivity of the human ear(20 Hz to 20 kHz) |most effective range is 1 kHz to 5.5 kHz |
infrasonic waves | below audible range(below 20 Hz) |volcanoes, earthquakes, thunder |
ultrasonic waves | above audible range(above 20 kHz) |animals like roaches & rodents |
speed of sound | v=331.4m/s + (0.606 m/s/°C)T > T is temp in degrees °C |depends on temperature of medium |
mach number | M=airspeed of object/local speed of sound |-ratio- of airspeed of an object to local airspeed of sound| compare speed of an object to speed of sound in the same air |
formula of pressure | p=F/A |pressure is the force per unit area| measure pressure of a longitudinal wave to find the amplitude |
sound intensity | W/m^2 - watts per square meter |amount of energy being transferred per unit area |
decibel(dB) | unit of sound level used to describe sound intensity level(not intensity)| 10^-12W/m^2 - 10^-8W/m^2 = 40dB(10,000 units) |decibel is one tenth of a BEL(B)| 0 to100 |
interference | when waves are traveling in opposite directions and meet a new wave is made |
free end reflection | reflection occurs at a media boundary where the second medium is less dense than the first medium |
media boundary | location where two media meet |
fixed end reflection | if a medium is fixed at one end the wave interacts with a more dense medium then the wave reaches the media boundary |
fixed end vs free end reflection | in a fixed wave reflection the orientation of the wave is reflected about the equilibrium point |