## Glossary of Physics 122

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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)