Periodic Motion and Wave (5/13) Flashcards
Amplitude
Extent of displacement
Factors of periodic motion
Amplitude
repeating cycle (period=T)
Frequency (1/T) or Hz
Cycle of periodic motion
Inertia: an object in motion tends to stay in motion
Restoring force: brings the object back to its equilibrium point (gravity)
At the midpoint
KE is max
PE is zero
At the extreme point where motion stops for fraction of a second
KE= 0 PE= max
Hooke’s law
F=-k*x
PE=1/2k*x^2
Pendulum period equation
T=2pisqrtL/g
Springs period equation
T=2pisqrtm/k
more mass=longer period
Mechanical waves
Physical pieces of mass that move back and fourth
Electromagnetic waves
oscillating electromagnetic fields
Transverse mechanical waves
Move up and down along y-axis. Only move on the vertical
Particles oscillate perpendicular to the direction of wave movement
Longitudinal waves
Particles oscillate parallel to the direction of wave movement
EX) sound
Ways to represent longitudinal waves
Compression and rarefaction (being bunched up then separated)
Sinusoidal
Amplitude= level of compression
Interference
When waves interact and create a wave with the sum of amplitudes
Constructive interference
Line up an amplitude increases
Destructive interference
Amplitude is smaller than largest amplitude or is zero when they perfectly are every other
Standing wave
Many waves overlapping and interfering with each other in a consistent manner
Points of no displacement
nodes
Points of maximum displacement
antinodes
Resonance frequency
object’s natural vibration frequency enabling maximum amplitude
Harmonics
One antinode- fundamental, wavelength= 2L
two antinodes- wavelength=L/1
three antinodes- wavelength=2/3L
Overall, wavelength=2L/N
Pipes
String at both ends: nth harmonic has n antinodes
open: nth harmonic has n nodes
Closed pip (closed at one end)
closed end has node and open end has antinode
Wavelength=4L
Overall, wavelength= 4L/n
n is a odd number
