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Heat & Thermodynamics - HW Pt 2 - Ch 24 - Thermodynamics



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

The first law of thermodynamics is a restatement of the
a.
Carnot cycle.
b.
law of heat addition.
c.
principle of entropy.
d.
conservation of energy.
e.
none of the above
 

 2. 

The greater the difference in temperature between the input reservoir and output reservoir for a heat engine, the
a.
less the efficiency.
b.
greater the efficiency.
c.
neither—efficiency doesn't depend on temperature difference.
 

 3. 

When mechanical work is done on a system, there can be an increase in its
a.
temperature.
b.
internal energy.
c.
both of the above
d.
none of the above
 

 4. 

When work is done by a system and no heat is added to it, the temperature of the system
a.
remains unchanged.
b.
decreases.
c.
increases.
 

 5. 

When a volume of air is compressed and no heat enters or leaves, the air temperature will
a.
increase.
b.
remain unchanged.
c.
decrease.
 

 6. 

Suppose the temperature of the input reservoir in a heat engine doesn't change. As the sink temperature is lowered, the efficiency of the engine
a.
stays the same.
b.
decreases.
c.
increases.
 

 7. 

Two identical blocks of iron, one at 10 degrees C and the other at 20 degrees C, are put in contact. Suppose the cooler block cools to 5 degrees C and the warmer block warms to 25 degrees C. This would violate the
a.
first law of thermodynamics.
b.
second law of thermodynamics.
c.
both of the above
d.
none of the above
 

 8. 

As a system becomes more disordered, entropy
a.
remains the same.
b.
decreases.
c.
increases.
 

 9. 

Systems that are left alone tend to move toward a state of
a.
more entropy.
b.
less entropy.
c.
no entropy.
 

 10. 

Entropy measures
a.
temperature as volume increases.
b.
temperature as pressure increases.
c.
temperature at constant pressure.
d.
messiness.
e.
temperature at constant volume.
 

 11. 

Entropy is closely related to the
a.
second law of thermodynamics.
b.
first law of thermodynamics.
c.
both of the above
d.
none of the above
 

 12. 

Running a refrigerator with its door open in a hot room makes the room
a.
cooler.
b.
warmer.
c.
none of the above.
 

 13. 

Cool a sample of air from zero on the Celsius scale to near zero on the absolute scale and the air loses
a.
volume.
b.
pressure.
c.
both A and B
d.
neither A nor B
 

 14. 

Ceramic automobile engines that can operate at higher temperatures will be
a.
less efficient.
b.
more efficient.
c.
neither of the above.
 

 15. 

The ideal efficiency for a heat engine operating between temperatures of 2050 K and 310 K is
a.
15%.
b.
50%.
c.
25%.
d.
85%.
e.
none of the above.
 

 16. 

80 joules of heat is added to a system that performs 55 Joules of work. The internal energy change of the system is
a.
0 J.
b.
25 J.
c.
55 J.
d.
135 J.
e.
none of the above.
 

A=True/B=False
Indicate whether the sentence or statement is true or false.
 

 17. 

It is possible to wholly convert a given amount of heat energy into mechanical energy.
 

 18. 

It is possible to totally convert a given amount of mechanical energy into heat.
 

 19. 

Systems left alone tend to move to a state of greater entropy.
 

 20. 

When work is done by a system on something else, the temperature of the system decreases.
 

 21. 

Efficiency in a heat engine is increased when there is a greater difference in input and output temperatures.
 

 22. 

If all the friction could be eliminated in a heat engine, its efficiency would be 100%.
 

 23. 

Whenever heat is added to a system, it transforms to an equal amount of some other form of energy.



(end of scantron section)
 

Essay:
 

 24. 

Use the example of a barn to illustrate that natural systems tend to proceed toward greater entropy.  Explain Entropy in your answer!
 

 25. 

Use gasoline in your car as an example to explain that energy becomes less organized when it transforms from one form to another.
 

Problem
 

 26. 

Calculate the ideal efficiency of a power plant that runs between temperatures 400 K and 150 K.
 

 27. 

If 5000J of heat is added to a heat engine but only 3500J of work is done by the engine, what happens to the remaining energy?
 



 
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