Modern Engineering Thermodynamics

Problems 53
Problems (* indicates problems in SI units)
1. Define the following terms: (a) thermostatics, (b) open system,
(c) extensive property, (d) equilibrium, and (e) zeroth law.
2. Define the following terms: (a) thermodynamics, (b) closed
system, (c) intensive property, (d) macroscopic analysis, and (e)
isolated system.
3.* A mixture of 1.0 kg of oxygen and 2.0 kg of hydrogen at
atmospheric temperature and pressure are placed in a closed
container. Explain (a) whether or not this mixture is a pure
substance, and (b) whether or not it is a homogenous substance.
4. Dry ice (solid CO 2 ) and CO 2 vapor are in a sealed rigid
container. Does the CO 2 in this system constitute (a) a pure
substance, (b) a homogenous substance, (c) a simple substance?
5. Which of the following are extensive properties?
(a) Temperature, (b) volume, (c) density, (d) work, (e) mass.
6. Are the following extensive or intensive properties? (a) Total
energy, (b) temperature, (c) pressure, (d) mass.
7. Identify whether the following properties are intensive or
extensive: (a) Specific energy, (b) total energy, (c) temperature,
(d) molar mass.
8. Explain how color could be a thermodynamic property and
indicate whether it would be an intensive or extensive property.
9. Let us say we have 2.00 ft 3 of a liquid/vapor mixture of motor
oil at 70.0°F and 14.7 psia that weighs 97.28. lbf where
g = 32.0 ft/s 2 . List the values of three intensive and two
extensive properties of the oil.
10.* There once was a man who had 1.00 m 3 of air at 20.0°EC and
0.100 MPa with a specific volume of 0.840 m 3 /kg. List the
values of three intensive and two extensive properties of his air
(Figure 2.13).
FIGURE 2.13
Problem 10.
Intensive properties
1.
Extensive properties
11. A woman once collected 2000. lbm of seawater at 50.0°F and
14.7 psia that occupied a volume of 56.0 ft 3 . List the values of
three intensive and two extensive properties of her seawater.
12. How many independent property values are required to fix the
state of a pure substance subject to only one work mode?
13. Determine whether the following statements are true or false:
a. The mass of a closed system is constant and its boundaries
are not movable.
b. An open system is defined as a system that can exchange
only heat and work with its surroundings.
2.
3.
1.
2.
c. An isolated system is completely uninfluenced by the
surroundings.
d. A thermodynamic property is a quantity that depends on the
state of the system and is independent of the process path by
which the system arrived at the given state.
e. When a system in a given state goes through a number of
processes and its final temperature is the same as the initial
temperature, the system has undergone a thermodynamic
cycle.
14. Identify the proper type of system (isolated, closed, or open) to
be used in the analysis of each of the following and explain the
reasons for your choice: (a) the Universe, (b) a kitchen
refrigerator, (c) an electrical generator, (d) a hydraulic pump,
(e) a living human being.
15. Determine the proper type of system (isolated, closed, or open)
to be used in analyzing each of the following items and explain
the reasons for your choice: (a) a bicycle, (b) a personal
computer, (c) a stereo system, and (d) a lawn water sprinkler.
16. Establish the correct type of system (isolated, closed, or open)
to be used in analyzing each of the following items and
explain the reasons for your choice: (a) the solar system,
(b) a carbonated drink dispensing machine, (c) an insulated
box of fruit buried deep in the ground, and (d) a lightbulb.
17. Which of the basic types of systems (isolated, closed, or open)
should be used to analyze each of the following items
and explain the reasons for your choice: (a) a flying insect,
(b) a black hole, (c) Niagara Falls, and (d) the great soaring
whipple bird of Mars.
18.* As chief engineer for Thermodynamic Analysts Inc., your job is
to determine the proper type of system (isolated, closed, or
open) to be used in analyzing each of the following items
submitted to your company and to explain the reasons for your
choice: (a) a water pistol, (b) a flashlight battery, (c) a rubber
boot, and (d) 2 kg chocolate fudge candy in a thermally
insulated box buried deep in the Andes mountains.
19. An alien spacecraft has abducted you from a NASA space station
and demands to know the type of system (isolated, closed, or
open) NASA uses to analyze each of the following items, plus an
explanation of the reasons for the choice: (a) the space station
itself, (b) your pocket computer, (c) a can of tuna fish, and
(d) an old Madonna movie.
20. An automobile internal combustion engine by itself is an open
system because it draws in air and exhausts combustion
products. How could one construct system boundaries around
an operating internal combustion engine to cause it to become a
closed system?
21.* Determine the specific volume of liquid water at 20.0°C that has
a density of 998.0 kg/m 3 .
22. Determine the mass of ammonia having a specific volume of
35.07 ft 3 /lbm in a container measuring exactly 3 ft by exactly
2 ft by exactly 1 ft.
23.* Determine the volume of liquid mercury with a density of
3.87 kg/m 3 having a mass of 2.00 kg.
24. A system consists of a mixture of 2.00 ft 3 of a liquid having a
density of 50.0 lbm/ft 3 and 4.00 lbm of a second liquid having
a specific volume of 0.0400 ft 3 /lbm. The specific volume of
the mixture in the system in ft 3 /lbm is (a) 0.208, (b) 2.08,
(c) 0.022, (d) 2.048, or (e) none of these.