Broderick Ch 24 Thermodynamics Review


Terms in this set (...)

What is the meaning of the Greek words from which we get the word thermodynamics?
heat/ temperature change
Is the study of thermodynamics concerned primarily with microscopic or macroscopic processes?
What is the lowest possible temperature on the Celsius scale? On the Kelvin scale?
-273, 0
What is the temperature of melting ice in kelvins? Of boiling water?
273, 373
How does the law of the conservation of energy relate to the first law of thermo- dynamics?
energy cannot be created or destroyed
1st law states heat in= work done + internal energy
What happens to the internal energy of a system when work is done on it? What happens to its temperature?
decreases the internal energy & the temperature
What is the relationship between heat added to a system and the internal energy and external work done by the system?
heat added= work done + internal energy
If work is done adiabatically on a system, will the internal energy of the system increase or decrease? If work is done by a system, will the internal energy of the system increase or decrease?
internal energy will decrease in both situations
What condition is necessary for a process to be adiabatic?
well insulated. energy cannot be lost or gained
What happens to the temperature of air when it is adiabatically compressed? When it adiabatically expands?
temperature of the air will increase. when it expands the energy will decrease so will the temperature
What generally happens to the temperature of rising air?
becomes cooler because there is less pressure the air expands
What generally happens to the temperature of sinking air?
more pressure the gas becomes denser and warms up
How does the second law of thermodynamics relate to the direction of heat flow?
heat flows from hot to cold
What three processes occur in every heat engine?
1. heat is added
2. energy flows from hot to cold
3. work is done
What is thermal pollution?
heat energy is escaping processes to increase the energy of our atmosphere
If all friction could be removed from a heat engine, would it be 100% efficient? Explain.
no, no engine can be 100% efficent because you can't cool the internal temperature to absolute zero
What is the ideal efficiency of a heatengine that operates with its hot reservoir at 500 K and its sink at 300 K?
Ideal efficiency= (Thot-Tcold)/Thot
Ideal efficiency= 0.4
Why are heat engines intentionally run at high operating temperatures?
must be a flow of hot to cold thermal energy and to do work the hotter they are the more efficient they are
Give at least two examples to distinguish between organized energy and disorganized energy .
gas in your car is organized and when it goes into the combustion engine it becomes disorganized
battery of a flashlight is organized and the light is disorganized
How much of the electrical energy transformed by a common light bulb becomes heat energy?
some becomes heat, some becomes light
With respect to orderly and disorderly states, what do natural systems tend to do? Can a disorderly state ever transform to an orderly state? Explain.
disorder. yes it can, work must be done
What is the physicist's term for a measure of messiness?
Under what condition can entropy decrease in a system?
work must be done
What is the relationship between the second law of thermodynamics and entropy?
the spontaneous flow of energy from hot to cold creates disorder or entropy