Week 2 Amp

Dynamics

study of effects/forces on state of an object or system of objects

Force

push or pull, interaction between 2 objects or between an object and its environment

What is force measured in?

Newtons

1 newton=

amt of force required to accelerate a 1 kg mass @ 1 m/s²

N1

inertia law, object at rest stays unless there’s an unbalanced force acting on it

Intertia

opposition of object to changes in its motion

Momentum=

mass x velocity

Momentum remains constant if…

no external force acts on the mass

N2

unbalanced force acting on object will cause object to move w/ an acceleration proportional to the force and inversely proportional to the mass of the object

Greater force=

higher acceleration

Greater mass=

lower acceleration

N3

equal and opposite direction, every force produces a counterforce that is equal in magnitude, and opposite in direction

Work formula

force x distance

When there is no displacement, there is

no work!

We measure work in…

J

Joules and work

amount of work needed to move 1 kg mass 1 m

Newton meter-work=

newton x meter

Energy

ability of object to do work

what is energy measured in?

Joules (same as work)

Energy= ____ work

future

work= _____ energy

used

Power

rate a system is going/losing energy

what is power measured in?

Watt

Watts are the system’s ability to do…

1 J of work in 1 second

Potential energy

mechanical, energy of object due to its position within a given physical system or environment

Main source of PE is…

GPE

Kinetic Energy

thermal, energy of motion object has due to its velocity

What law is about potential and kinetic switching back and forth forever?

Law of Conservation of Energy

Closer to equilibrium=

elasticity low, velocity high

Free vibration

back and forth vibration of a system where no additional energy is added to system once it’s originally set in motion

Resonance

natural state of a vibrating system

Resonance frequency

frequency of free vibration

Interactions between ______ and ______ determine the frequency of the back and forth movement in a vibrating system

force of elasticity, inertia

Larger masses= ____ resonance frequencies

lower

Friction

force that opposes the relative motion or tendency to such motion of 2 bodies in contact

Friction for mass spring systems is ____, and friction for kinetic energy is ______

surrounding air surfaces and air particles, thermal energy (heat)

Damping

gradual decrease in amplitude energy in a vibrating system due to its dissipation in the surrounding environment,

Forced Vibration

system forced to vibrate by periodically/continuously applied external force (not allowed to vibrate freely)

The driving frequency of forced vibration is______

frequency of external force

Magnitude of vibrations depend on…

magnitude of applied force and frequency of periodic driving force

When you match driving frequency and resonance frequency…

system will vibrate at a greater magnitude (bridges collapse)

What is the most fundamental back and forth motion, rarely seen in nature?

SHM

Complex

sum of 2 or more vibrations, has frequency components

Fourier Theorem

any oscillatory (vibratory) motion is the sum of various sinusoidal motions of varying amplitude, frequency, and phase

Waveform Synthesis

process of combining several individual sinusoidal motions into a complex waveform

Sound deals with a form of motion called _____

harmonic motion!

Harmonic Motion

mechanical disturbance, propagated through an elastic medium

Sound waves are _____ waves

complex (every sound we hear, most sounds, many simple saves, periodic vs aperiodic

Harmonics

frequency components of a complex waveform that are whole-number multiples of its fundamental frequency

What do harmonics result in?

periodic vibration

First harmonic

fundamental frequency of complex periodic waveform, Lowest frequency of a periodic waveform

2nd and 3rd harmonic

2x fundamental, 3x fundamental

No GCF=

aperiodic wave

Missing fundamental

no energy at fundamental frequency, Occurs when a complex periodic wave doesn’t have a component equal to the fundamental frequency 

A wave allows for transport of energy without the transportation of______

matter

Wave

change from equilibrium, a disturbance or oscillation

Transverse wave motion

up and down, Vibration of medium is 90 degrees re: direction of wave propagation

Longitudinal Wave motion

particle displacement is parallel to wave of propagation, particles oscillate back and forth around a set equilibrium point

sound pressures are ________ waves

longitudinal pressure

A wave occurs from a _____ of a medium

compression (condensation)

What follows compression

expansion of medium (rarefaction)

Condensation is ____ from source

away

Rarefaction motion is _____the source

towards

Sound Propagation

It is the succession of molecules being pushed together & pulled apart that creates sound wave motion

wavelength

(λ) is the physical distance in space occupied by one period of a wave. 

The distance between two subsequent compressions (two rarefactions of a sound wave is called the_______

wavelength

wavelength is the distance between two subsequent ______ of a transverse wave

crests/troughs

wavelength depends on…

speed and frequency of the sound

wavelength formula

wavelength= c/f

Sound pressure

Magnitude of change in the local atmospheric pressure caused by the vibration of the sound source 

Sound pressure is the amount of _____ moving air molecules per unit area

force

Sound pressure formula

f/a, measure in Pa

Sound intensity

The amount of sound power that travels through a specific area of the wavefront surface. THE AMOUNT OF SOUND ENERGY THAT PASSES THROUGH A SPECIFIC AREA IN ONE SEC

Wavefront

an imaginary line connecting the leading point of a wave propagating through a medium 

Sound intensity formula

sound power/area (W/m²)

To calculate how much energy is reaching a crowd in the audience, you need to calculate…

sound intensity

Inverse square law

sound intensity is inversely proportional to square of distance from source (6 dB drop-off)

As the distance from the sound source doubles, sound intensity ______

decreases by 6 dB

What 3 things are required for SOUND to occur?

energy source, vibrating medium, elastic medium

Time domain graph

Time waveform of sound pressure versus time

Spectrum

Frequency content of an acoustic signal

Spectrogram

uses both frequency and time information to display sounds

A spectrum is a graphical representation of a _____________, showing the _______________ on the y axis, of the individual components in order of ____________on the x-axis

complex waveform, waveform energy (amplitudes), frequency

A ________ shows time domain

waveform

spectrum components are

graphical representation of Fourier series

A spectrogram graphs

time and frequency on the same figure! (and amplitude too!)

What information does a time domain graph give you in terms of sound wave? How is this different from a spectrogram?

A time domain graph will show the time waveform of sound pressure versus time. A spectrogram is different because you graph both time and frequency information to represent a sound, showing its amplitude as well.