Oscillations and Waves (Physics)

Periodic Motion

Periodic Motion

Any motion that repeats itself over the same pathway.

Simple Harmonic Motion (SHM)

Periodic motion that occurs because of a restoring force (always trying to get back to the equilibrium point). Ex: swinging mass/pendulum or mass on a spring.

Vibration

back and forth motion

Frequency

cycles/time (Hz)

Period

1/f (inverse of frequency)

Pulse

a single disturbance

Wave

a vibration (series of pulses) that move out through space

Sine Wave

a pictorial representation of waves

Crest

top of wave (highest point)

Trough

lowest point of wave

Equilibrium

resting position/middle position

Amplitude

maximum displacement from equilibrium. measures strength and energy of a wave.

Wavelength

distance from any 2 identical successive parts of a wave. Ex: crest to crest, trough to trough, etc.

Medium

what a wave passes through. Ex: air, water, slinky, etc.

Mechanical Wave

needs a medium to travel. Ex: sound waves

Electromagnetic Wave

doesn’t need a medium to travel. Ex: light waves

Transverse Wave

vibration is perpendicular to wave motion

Longitudinal Wave

vibration is parallel to wave motion

Compression aka Condensation

area of high pressure

Rarefaction

area of low pressure

Surface Waves

combination of transverse and longitudinal waves

Principle of Superposition

When waves occupy the same space at the same time = resultant wave = sum of amplitudes

Interference

when wave amplitudes combine

In Phase

same part of the waves arrive at the same time

Out of Phase

different parts of the wave arrive at the same time

Constructive

when two waves undergo superposition in phase = bigger amplitude

Destructive

when two waves undergo superposition out of phase = smaller amplitude

Standing Wave

when two identical waves move in opposite directions and interfere

Nodes

parts of a wave that don’t move (no displacement) - destructive interference

Antinodes

parts that move (maximum displacement) - alternating constructive and destructive interference. there is always one more node than antinode.

Damped Harmonic Motion

when something loses energy during simple harmonic motion (friction/air resistance)

Under-Damped

a little bit of friction. (takes a long time to return to equilibrium + oscillates a lot).

Over-Damped

takes a long time to return to equilibrium (no oscillations).

Critically Damped

settles to equilibrium quickly without a lot of oscillations.

Resonance

when natural frequency = forced vibration you get resonance and an increased amplitude.