Physics 122
Terms
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 System

amount of matter enclosed by boundaries and surfaces
described by P, V, T  Heat resevoir
 Large seperate system with unlimited heat capacity; heat entering/leaving system comes from or goes to it
 State
 specific combination of variables P,V,T
 Equation of State
 Relates the state variables
 Process
 A change in the system or state variables
 Zeroth law
 if T1=T2 and T2=T3 then T1=T3
 First Law

Conservation of Energy
Q = /_\U + W  When heat enters system
 Temp increases, change in U is positive
 If w positive
 System does work
 If w negative
 System is worked upon
 Heat leaves
 temp decreases, delta U is negative
 Work done
 area under the curve
 Isothermic

Change done under constant temperature; delta U = 0 so
Q = W  Isobaric

Change done under constant pressure
W = p*deltaV  Isometric

Change done under constant volume
W=0; Q = deltaU  Adiabatic

No heat transfered in or out
Q=0 so W = deltaU
(steeper than isotherm)  entrophy
 measure of disorder
 reversible process
 a system returns to its initial state by tracing its initial process backwards
 Second law

heat will not flow spontaneously from a cold object to a hot object
all natural processes move to a state of higher disarray  Engines and pumps as relates to the first law
 Total heat input = total heat output (and work)
 Heat engine

converts heat E to work; takes h from hot resevoir, does work, expells excess heat into cold resevoir
want to max work  thermal pump
 Transfers heat from cold resevoir to hot
 coefficient of performance
 measures efficiency of therm pump for refridg and heat pump
 carnot cycle

most efficient cycle for heat engine,
2 adiabatic and 2 isothermal processes  carnot efficiency
 deals in temperatures, max eff for heat engine !in kelvin
 Third law
 As system approaches 0 K, all process begin to stop, entrophy reaches minimum value
 simple systems
 single bodies of mass
 periodic motion
 motion that repeats itself
 equilibrium
 resting point of the system
 amplitude
 maximum displacement of mass
 period
 length of time for one cycle
 frequency
 number of cycles per unit time
 simple harmonic motion
 motion that can be described sinusoidally
 if motion starts at 0
 sin
 if motion starts at displacement y=A
 cos
 angular frequency
 how fast object is oscillating in rad/s
 phase shift
 change in initial displacement
 wave
 disturbance passing through medium carrying energy
 periodic wave
 continuous wave that moves sinusoidally
 wavelength
 spatial length of one cycle
 traveling wave
 dependent on time and displacement
 +/

+ if wave moves to left
 if wave moves to right  transverse wave
 particles oscillate perpendicular to wave
 longitudinal wave
 particles oscillate parallel to wave motion
 interference
 behavior of two waves in the same region
 Constructive interference
 amplitude of the waves is summed
 Destructive interference
 amplitude of waves is less than either individual, if same amp, cancel each other out
 reflection

wave strikes boundary and is reflected back into initial medium
fixed  inverted
free  wave is same  refraction
 wave bends when entering different medium, depends on speed change
 dispersion
 waves at different frequencies refract at different angles in a medium
 diffraction
 bending of waves around obstructions (if same or smaller size than wavelength)