Physics 2 First Test

Simple Harmonic Motion

Occurs when a motion is repetitive, the motion is due to a restoring force, and the period is independent of the amplitude 

Examples of Simple Harmonic Motion

Sound/Light Waves, Pendulum, Mass-Spring Systems

Restoring force

force that brings an object back to equilibrium

Hooke’s Law (describes the restoring force of a SPRING)

F=-kx

Amplitude (A or x)

maximum pos/neg displacement from equilibrium point

Period (T)

time required to complete one cycle +max to -max

Frequency (f)

number of cycles completed in one second

At equilibrum, what variables are at what values

v=max

A and F=0

At Amplitudes, what variables are at what values

V=0

A= max, but OPPOSITE direction to displacement

F= max

Simple Pendulum

swinging device where all the mass is at the bob and the string does not stretch and swings less than 15 deg

Vmax

2πfA

Amax

4π²f²A

Period of a mass-spring oscillator

T=2π sqrrt m/k

Period of a pendulum

T=2π sqrrt L/g

KE is present when something

moves

Us is present when something

is stretched or compressed

Mechanical Energy formula

E= 1/2kA² + 1/2mv²

max KE occurs at, max Us occurs at

equilibrium, amplitudes

At what position x will the KE equal Us?

x= A/ rt2

Damped Harmonic Oscillations

are oscillations in a system that gradually decrease in amplitude due to an energy loss, often caused by friction

What does damping result in?

lower amplitude, acceleration, and velocity

Critical damping

prevents oscillations

Resonance

when an object is driven to its natural frequency, resulting in increased amplitude of oscillation.

Pulse

a singular wave moving through a medium

What is speed of the pulse affected by?

Tension and density of the string

At a fixed boundary, a wave is

inversely reflected (undergoes a 180 phase shift)

At a moveable boundary, a wave is

directly reflected (no phase shift, just turns back around)

Waves are the motion caused by

a disturbance

Mechanical waves

waves that require a medium for transmission

electromagnetic waves

do not require a medium for transmission

Transverse waves

travel perpendicular to the direction of the vibrations

Longitudinal waves

travel parallel to the direction of the vibration

wavelength of a transverse wave

one full crest and one full trough

compression of a longitudinal wave

where particles pack close together (like a crest in a transverse wave)

refraction of a longitudinal wave

where particles are spaced apart (like a trough in a transverse wave)

wavelength of a longitudinal wave

one full compression and one full refraction

v=

frequency x wavelength OR distance/time

constructive interference

crest overlaps with crest; amplifies wave

point of max constructive interference is called

antinode

destructive interference

crest overlaps with trough; diminishes wave

point of max destructive interference

node

beat frequency

The frequency resulting from the interference of two waves of slightly different frequencies, perceived as a pulsing sound.

standing wave fundamental frequency formula

f = v/2L

standing wave is produced when a string

is vibrated at perfect frequency

open air columns have less or more nodes than antinodes?

less nodes

closed air columns have less or more nodes than antinodes? and do closed air columns have even or odd harmonics?

the same number of nodes and antinodes; and ODD harmonics only

Do standing waves have less or more nodes than antinodes?

more nodes

can a longitudinal wave transmit in a vacuum?

no

speed of a wave depends on

temperature, density and elastic properties of material

pitch

frequency of wave

subsonic

20 Hz

ultrasonic

20,000 Hz

longitudinal wave speed formula Vs

Vs= (331) root (1 + T/273)

Intensity formula

I= P/A

Area for surface area of a wave from a source

4πr²

Decibel scale

measures the intensities of sound in decibels

Threshold of hearing

1.0×10^-12 W/m²

Threshold of pain

1.0 W/m²

dB formula

10 log (I/I₀)

The Doppler Effect

apparent shift in frequency due to relative motion of wave source and wave observer

Doppler Effect Formula

f' = f (v ± v₀) / (v ± vs)

Sonic Booms

loud sounds produced when an object moves faster than the speed of sound, causing pressure waves to compress.

linear mass density formula

u= mass/length

velocity formula involving mass density and force

v= F/ rt u