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Physics 122


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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
specific combination of variables P,V,T
Equation of State
Relates the state variables
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
Change done under constant temperature; delta U = 0 so
Q = W
Change done under constant pressure
W = p*deltaV
Change done under constant volume
W=0; Q = deltaU
No heat transfered in or out
Q=0 so -W = deltaU
(steeper than isotherm)
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
resting point of the system
maximum displacement of mass
length of time for one cycle
number of cycles per unit time
simple harmonic motion
motion that can be described sinusoidally
if motion starts at 0
if motion starts at displacement y=A
angular frequency
how fast object is oscillating in rad/s
phase shift
change in initial displacement
disturbance passing through medium carrying energy
periodic wave
continuous wave that moves sinusoidally
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
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
wave strikes boundary and is reflected back into initial medium
-fixed - inverted
-free - wave is same
wave bends when entering different medium, depends on speed change
waves at different frequencies refract at different angles in a medium
bending of waves around obstructions (if same or smaller size than wavelength)

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