Physics Ch. 15-18 Test
What is the temperature of freezing water in Celsius
0 C
the second law of thermodynamics makes it impossible to attain a temperature of...
0 K
entropy is closely related to the
2nd law of thermodynamics
The mechanical equivalent of heat in the SI system is...
4.18 J/cal
What is the difference between a calorie and a joule?
4.18j=1 cal
What is an example of radiation?
A black object radiates heat
How does a heat pump differ from a heat source?
A heat pump is a device that changes thermal energy into mechanical work. A heat source just has a greater temperature than its environment.
Example of conduction?
A pot sitting on a hot burner. A burning stove and my hand.
what is the third type of heat transfer?
Radiation
State the first law of thermodynamics
The change of internal energy of a closed system will be equal to the heat added to the system minus the work done by the system. (Energy cannot be created nor destroyed)
What is thermodynamics?
The study of processes in which energy is transferred as heat and as work.
What is internal energy?
The sum total of all the energy of all the molecules in a system.
state the law of entropy
The total entropy of any system plus that of its environment increases as a result of any natural process. Natural processes tend to move toward a state of greater disorder.
The molecules in a room-temperature glass of water jostle around at
a great variety of speeds
What is an ideal heat engine?
a heat engine in which each of the processes of heat addition and exhaust, of gas expansion or compression, were considered to be done reversibly
What is an isothermal process?
a process that occurs at constant temperature
second law of thermodynamics
heat flows from hot object to cold object, not the other way around
Increased air pressure on the surface of hot water tends to
prevent boiling
What is conduction?
Heat transfer within a material or between materials that are touching
Why does silver heat up more quickly than water?
It has a lower heat capacity
In the Joule experiment, no heat enters or leaves the insulating jar. The water-churning process is therefore an..... one
adiabatic
Why is condensation a warming process?
because the gas releases energy
When mechanical work is done on a system, there can be an increase in its
both temp and internal energy
The first law of thermodynamics is a special case of the...
conservation of energy
during an adiabatic expansion, the internal energy...
decreases
when the volume of a gas increases isothermally, its pressure... and its temperature remains...
decreases... constant
When the volume of a gas increases adiabatically, its pressure... and its temperature...
decreases... decreases
natural processes tend to increase... in the universe
entropy
Work done by a gas is considered positive when the gas.... and its temperature remains...
expands... decreases
the source of the heat equivalent of work done by an ideal gas during isothermal expansion is its... while the source of the heat equivalent of work done by an ideal gas during adiabatic expansion is its...
heat input at high temperature... internal energy of the gas
What is convection?
heat transfer in a fluid in which hot fluid rises and cold fluid sinks, setting up a cycle
Example of convection
hot air rising
When a volume of air is compressed, its temperature
increases
Suppose you put a closed, sealed can of air on a hot stove burner. The contained air will undergo an increase in
internal energy, temp, and pressure
What change in operating conditions increases the efficiency of an ideal heat engine?
lowering the lower operating temperature/raising the higher operating temperature
Systems that are left alone, tend to move toward a state of
more entropy
When heat is converted to another form of energy, or vice versa, there is... loss of energy
no
During an adiabatic compression of an ideal gas
no heat is supplied to or removed from the gas
What is an adiabatic process?
one in which no heat is allowed to flow into or out of the system
To totally convert a given amount of mechanical energy into heat is
possible
When a gas is changed to a liquid state, the gas
releases energy
During an isothermal expansion, the internal energy....
remains constant
Give an example of a heat pump
steam engine
Define specific heat
the heat required to raise the temperature of the unit mass of a given substance by a given amount
Evaporation is a cooling process because
the more energetic molecules are able to escape the liquid
Entropy is the amount of energy that cannot be converted into...
useful work
a temperature inversion occurs when the upper layers of air are
warmer than the lower regions of air