8/18 Pressure/Energy/Thermodynamics

Pressure is like a

Potential Energy

Can pressure be stored?

Yes

Pressure is NOT

an Energy, but it’s similar

Pressure and Energy can spontaneously

go High to Low

Thermodynamics is the study of

Thermal Energy

Thermodynamics in some ways

the ultimate form of energy

Thermodynamics deal with

Internal and External Systems

Thermodynamics is the form of

Internal Kinetic motion of matter

Potential energy stored in the internal structure of matter is

Specific Heat (related to)

Some of the energy cannot be transferred like

the spin of an electron or the random motion of atoms

The sign for Temperature is

T

Temperature measures

the average INTERNAL kinetic energy

Temperature is separate

from the EXTERNAL 1/2mv²

The Unit for Temperature is

Kelvin

It is the same gradient as Celsius,

but referenced to absolute zero (-273*C, 1*C = 1K)

Molecules in objects with more thermal energy

move faster (more internal Kinetic Energy)

Absolute Zero means

No movement at all

Heat is

not hot

Heat (Q) is

the flow of thermal energy

Heat only flows from

high to low, without Work

Heat stops flowing when

objects reach thermal equilibrium (same temperature) (0th Law)

Cold is simply the

absence of heat

The direction of heat flow determines

the feelings of hot and cold

Zeroth Law of Thermodynamics

If System A is in thermal equilibrium with System B AND System B is in thermal equilibrium with System C, then System A is in thermal equilibrium with System C (All systems seek thermal equilibrium with each other)

For systems where only thermal energy changes,

the change in thermal energy is equal to the net heat flow of the system and/or the NET work done on or by the system

Change in thermal energy of the system is equal to

the sum of all work plus the sum of the heat flow, in and out of the system (This is a statement of conservation of energy)

Q is positive when it

flows into a system

W is positive when it is

done on a system

Q is negative when

it flows out of a system

W is negative when the

system does work

No process can be

100% efficient (entropy - a tax on any transfer of energy)

Entropy provides an upper limit to the

efficiency of any process

Entropy is proportional to

disorder

Kavg =

3/2kBT

K =

Average Kinetic Energy (of 1 molecule)

kB =

Boltzmann’s Constant

T =

Temperature

Heat flow (Q) occurs

via elastic collisions of molecules (of a liquid or gas)

Heat flows from

High Temperature (High Kavg) to Low Temperature (Low Kavg)

Low energy molecules

gain KE

High energy molecules

lose KE