Physics CH 11: Harmonic Motion

Simple Harmonic Motion

vibration about an equilibrium position in which a restoring force is proportional to the displacement from equilibrium

Restoring Force

a force that acts to bring an object back to equilibrium

Damping

the gradual loss of amplitude of something in harmonic motion; due to friction

Hooke's Law

restoring force = -displacement x constant

pendulum

A device that swings back and forth due to the force of gravity

bob

a mass at the end of a pendulum

gravity

source of restoring force in pendulum

gravity and spring force

sources of restoring force in mass-spring systems

amplitude

For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position.

Period (T)

time taken for one complete vibration

Frequency (f)

the measure of how many oscillations per time

Hertz

the unit of frequency, equal to one cycle per second

reciprocal

relationship between frequency and period

length and gravity

factors that affect period of a pendulum

mass and spring constant

factors that affect period of a spring system

wave

A disturbance that transfers energy from place to place

mechanical wave

A wave that requires a medium through which to travel

medium

Material through which a wave travels

electromagnetic waves

transverse waves consisting of changing electric fields and changing magnetic fields

pulse

a single wave through a medium

periodic wave

A repetitive series of connected pulses

transverse wave

A wave in which the particles of the medium move perpendicularly to the direction the wave is traveling

longitudinal wave (compression wave)

A wave in which the vibration of the medium is parallel to the direction the wave travels

rarefaction

a part in a longitudinal wave where the particles are spread apart

compression

The part of a longitudinal wave where the particles of the medium are close together.

superposition of waves

Overlap of two waves at a point in space

constructive interference

The interference that occurs when two waves combine to make a wave with a larger amplitude

destructive interference

The interference that occurs when two waves combine to make a wave with a smaller amplitude

At a fixed boundary, waves are

reflected and inverted

At a free boundary, waves are

reflected but not inverted

standing waves

-produced by perfect and in sync interference of traveling wave and reflected wave

node

A point of zero amplitude on a standing wave

antinode

A point of maximum amplitude on a standing wave