Accel physics waves unit

wave

starts with a disturbance that carries energy through matter (a medium) or space

travels through matter without transferring matter

transverse waves

particles vibrate perpendicular to the motion of the wave

particles move ____while energy travels ____

up and down; side to side

chest

top of the wave/particles motion

trough

bottom of the wave/particles motion

equilibrium

particle’s original position (halfway between crest & trough)

Amplitude (A, meters)

max distance particles move from equilibrium

wavelength (meters)

horizontal length of one cycle of motion (crest to crest, trough to trough)

Period (T, seconds)

the time to complete one cycle of motion

Node

The point where the wave is on equilibrium

reflection at loose/free boundary

waves are reflected back on the same side of the equilibrium

ex: rope pushes on wall to the right, wall pushes rope back in the other direction (left)

reflection at fixed boundary

waves are reflected back and inverted (flipped)

ex: rope pushes on wall up and right. wall exerts equal and opposite force on rope

principal of superposition

we can add the amplitudes of two pulses when they come together

constructive interference

pulses on the same side of equilibrium. add on top of each other, to create a larger pulse

destructive interference

pulses meet eachother on opposite sides of equilibrium

form a smaller wave, may cause no visible wave

AM

amplitude modulation

FM

frequency modulation

two waves a wave can travel

longitudinal wave or compressional wave and transverse waves

longitudinal waves

particles that vibrate parallel to the wave

compresion

wher the molecules are compressed together (high density)

rarefaction

where there is low density (stretched out)

what creates sound?

tiny changes of air pressure created by some sort of vibration

ex: longitudinal wave

• compression: high density/pressure of air molecules

• rarefaction: low density/pressure of air molecules

how does changing frequency affect pitch?

frequency = pitch

pitch: how we perceive frequencies of sound

high frequencies, high pitch

how does changing amplitude affect sound?

amplitude= volume/air pressure

high amplitude, high volume

Type of medium

influences the speed of sound b/c particles are closer together in solids so they will hit each other faster and sound will travel faster

Temp of medium

influences the speed of sound because high temperature means particles are moving faster and the sound will travel faster

doppler effect

as you or a source of sound waves is moving, the frequency at which you hear the wave changes and we hear a change in pitch

higher pitch

source is moving towards you

lower pitch

source is moving away from you

resonance

phenomenon that occurs when an object is vibrated at its natural frequency.

results in an increased amplitude of vibration