2nd Law Flashcards
it states that heat will never of itself flow from a cold object to a hot object
Second law of thermodynamics
heat flows from __________ to _________
hot
cold
TRUE/FALSE
According to the 2nd law of thermodynamics, no heat engine can convert all heat input to mechanical energy output
TRUE
-system/device for converting heat into work
heat engine
in a mechanical heat engine heat is taken from a _____ source and mechanical work is done and the heat is expelled at a _________ temperature
HIgh
lower
EVery heat engine will increase its internal energy by ______________
absorbing heat from a reservoir of higher temperature
TRUE/FALSE
Every heat engine will convert some of its energy into mechanical work
TRUE
TRUE/FALSE
Every heat engine will expel the remaining energy as heat to some lower temperature reservoir
When heat energy flows from a high temperature place to a lower temperature place, part of this energy is _______________
transformed into work output
a heat engine operating in reverse
refrigerator
TRUE/FALSE
It is not possible to have a process where the only result in the extraction of heat from a reservoir and the conversion of all this heat into work
TRUE
TRUE/FALSE
It is not possible to have a process where heat is removed from a reservoir at one temperature and absorbed in equal quantity by a reservoir at a higher temperature
TRUE
It states that when work is done by a heat engine running between two temps, Thot and Tcold, only some of the input heat, Thot, can be converted to work, the rest will ecpelled as heat Tcold
second law of thermodynamics
TRUE/FALSE
There is always heat exhaust, which may be desirable or undesirable
TRUE
an undesirable expelled heat
thermal pollution
Sadi Carnot’s discovery states that:
“the _____ fraction of heat that can be converted to work, even under ideal conditions, depends on the __________ between the hot reservoir and the cold sink
upper
temperature
Given any 2 operating temperatures, there exists an ideal heat engine called a _______________, operating in a __________.
Carnot engine
Carnot cycle
4 process (carnot cycle)
1. The gas expands ____________ at temp. Th (AB), absorbing heat Qh.
2. It expands __________ (BC) until its temp drops to Tc
3. It is compressed __________ (CD) expelling heat Qc
4. It compressed ________ back to its orig. state (DA)
isothermally
adiabatically
isothermally
adiabatically
the ideal maximum percentage of input energy that the engine can convert to work
Carnot efficiency or ideal efficiency
TRUE/FALSE
increasing the temp. cause an increase in the efficiency
TRUE
TRUE/FALSE
No work output is possible for any heat engine unless a temperature difference exists between the reservoir and the sink. zero efficiency.
TRUE
When a physical system can distribute its energy freely, entropy _______ and energy of the system available for work _________
increases
decreases
entropy (increases/decreases) in physical systems
increases
When there is work input, entropy _________
decreases
this law is a universal law of nature for which no exceptions have been observed
First law of thermodynamics
This law is a probability statement. Disordered states are much more probable than ordered states
Second law of Thermodynamics
Measure of probability of having particular states
entropy
