THeRMO PRELIM Flashcards
An expression of the principle of conservation of energy which states that energy cannot be
created or destroyed but can only be transformed or changed from one form to another.
FIRST LAW OF THERMODYNAMICS
_____ and ______ are means by which we can transfer or
transform energies from one form to another.
Work and Heat Flow
True or False:
Work and Heat flow can exist without energy
False. There will be no work and heat flow without energy
The energy possessed by a body by virtue of its POSITION
Potential Energy, PE. Note: POSITION
The energy possessed by a body by virtue of its MOTION.
Kinetic Energy, KE. Note: MOTION
The energy stored in a system in microscopic scale.
Internal Energy, U
In a system (w/ molecules inside), how is KINETIC ENERGY present?
The MOTION of molecules causes KE.
- Thru vibration, translation, and rotation
In a system (w/ molecules inside), how is POTENTIAL ENERGY present?
The BINDING ENERGY (Molecular attractive forcess) are associated with PE.
Under PE, what holds the atoms together in a system?
BINDING ENERGY
True or False:
In our naked eye, a steady glass of water means there is no motion in molecules.
FALSE
there is a mass of high-speed molecules moving at hundreds of meters per second @ microscopic scale
The energy required to MOVE A MASS (thermodynamic substance) that enters a thermodynamic system from one point to another.
Flow work or Flow energy
What causes a continous flow of mass in the Thermodynamic system
FLOW WORK or FLOW ENERGY
In a flow work
The __________ enters the thermodynamic system and is pushed by the surroundings against the _________ and ____________ in the thermodynamic system, providing the system with ___________ in the process.
MASS;
RESISTANCE and LOCAL PRESSURE;
WORK;
The sum of the internal energy and the work flow
Enthalpy, H
Energies are transformed or transferred in two ways – by ________ or __________
Heat or Work
the transfer of energy between two bodies because of its temperature difference.
Heat Energy or Thermal Energy, Q
True or False
Energy CAN flow from low to high temperature
FALSE.
Energy ALWAYS flows from high to low energy, increasing Entropy.
Heat flow will continue as long as there is ____________________ (2 words)
Temperature Difference
a (positive or negative?) sign Q denotes that the heat is added on the system
or the direction of heat is going into the system
POSITIVE (+)
(positive or negative) sign Q denotes that heat is rejected by the system or the direction
of heat is going out of the system.
NEGATIVE (-)
a measure of the amount of energy that is UNAVAILABLE to do useful work in a closed system undergoing a change of state.
Entropy, S
describes the microscopic disorder or degree of randomness of molecules in a closed thermodynamic system
ENTROPY, S
Which Law of Thermodynamics
It states that the thermal energy in a closed system disperses over time until it reaches equilibrium.
2ND LAW OF THERMO.
True or False:
As entropy increases, energy available to do useful work also increases
FALSE; Energy and Entropy are inversely proportional to each other
When energy disperses, the pressure, temperature
and density __________ , therefore __________ (less or more?) energy is now available to do useful work.
Evens out;
Less
True or False
Thermal Equilibrium increases Entropy
TRUE
Energy is transferred through __________ when force, F, is applied to a body that causes it to move or displaced at a distance, d.
WORK
the rate of doing work, expressed as amount of work per unit time or sometimes in horsepower.
POWER
___________ states that the the mass going in the system is equal to the mass going out of the system
Conservation of Mass
(positive or negative?) sign Work (W) denotes that the work is done by the system or the direction of work is going out the system
POSITIVE
(positive or negative?) sign Work (W) denotes that work is done on the system or the direction of heat
is going into the system.
NEGATIVE
Another term for thermodynamic system
Control volume
defined as a region in space that is under consideration, it also contains mass or a thermodynamic substance.
It has specific boundaries that separate it from the external effects of the environment.
Thermodynamic System or Control Volume
2 types of Thermodynamics systems
– Open Systems (Steady-flow systems)
– Closed systems (Non-flow Systems)
A system able to exchange energy (heat and work) and mass across the system boundary
– Open Systems (Steady-flow systems)
A System able to exchange energy (heat and work) across the system boundary but not mass.
– Closed systems (Non-flow Systems)
