Since the states visited in the process fall
into the realm where the ideal gas model applies, the
value of work determined using the ideal gas model agrees
with Steam Table data, as expected.
A system consisting of 1 kg of H2O undergoes a heat pump cycle composed of the following
Process 1-2: Constant-volume heating from p1 = 5 bar, T1 = 160oC to p2 = 10 bar.
Process 2-3: Constant-pressure cooling to satura
As shown in Fig. 3.111, a piston-cylinder assembly fitted with a paddle wheel contains air,
initially at p1 = 30 lbf/in.2, T1 = 540oF, and V1 = 4 ft3. The air undergoes a process to a final state
where p2 = 20 lbf
A closed, rigid tank is filled with a gas modeled as an ideal gas, initially at 27oC and a gage
pressure of 300 kPa. The gas is heated, and the gage pressure at the final state is 367 kPa.
Determine the final temperature, in oC
Determine the volume, in m3, occupied by 2 kg of H2O at 100 bar, 400oC, using (a) data from the
compressibility chart, (b) data from the steam tables.
Compare the results of parts (a) and (b) and discuss.
V = ?
m = 2 kg
p = 1
Five kg of butane (C4H10) in a piston-cylinder assembly undergo a process from p1 = 5 MPa, T1 =
500 K to p2 = 3 MPa during which the relationship between pressure and specific volume is pv =
Check the applicability of the ideal gas model for
(a) for water at 600oF and pressures of 900 lbf/in.2 and 100 lbf/in.2.
(b) for nitrogen at -20oC and pressures of 75 bar and 1 bar.
Check the applicability of the ideal gas mod
PROBLEM 3.100 (Continued)
Table A-1 gives: Tc = 133 K and pc = 37.7 bar. Thus
p < 3.77 bar; Z is in the acceptable range for all temperatures
for T = 266 K; p < 271 bar
for T = 333 K; p < 189 bar
for T = 466 K; p < 132 bar
for T > 665 K; p < 121 bar
Problem 4.43 The unstretched length of the spring is
1 m, and the spring constant is k = 20 N/m. If = 30 ,
what is the moment about A due to the force exerted by
the spring on the circular bar at B?
Solution: Assume that the bar is a quarter c
Problem 4.85 The robotic manipulator is stationary.
The weights of the arms AB and BC act at their midpoints. The direction cosines of the centerline of arm
AB are cos x = 0.500, cos y = 0.866, cos z = 0,
and the direction cosines of the centerline of arm
Problem 4.50 The line of action of F is contained in
the x y plane. The moment of F about O is 140k (Nm), and the moment of F about A is 280k (N-m). What
are the components of F?
A (0, 7, 0) m
(5, 3, 0) m
Solution: The strategy is to nd the moment
Problem 4.68 In Problem 4.67, determine the moment about point D due to the force exerted on the ring
A by the cable AB.
Solution: We need to write the forces as magnitudes times the
appropriate unit vectors, write the equilibrium equations for A in compo
Problem 4.78 Use Eqs. (4.5) and (4.6) to determine
the moment of the 20-N force about (a) the x axis, (b) the
y axis, (c) the z axis. (First see if you can write down
the results without using the equations.)
(7, 4, 0) m
20 k (N)
Solution: The force
Problem 4.73 The force F = 800 lb. The sum of
the moments about O due to the force F and the forces
exerted at A by the cables AB and AC is zero. What
are the tensions in the cables?
(0, 6, 10) ft
(8, 6, 0) ft
(0, 10, 4) ft
Problem 4.134 Systems 1 and 2 each consist of a
couple. If they are equivalent, what is F ?
For couples, the sum of the forces vanish for both systems. For System 1, the two forces are located at r11 = 4i, and
r12 = +5j.
Problem 4.12 Two students attempt to loosen a lug
nut with a lug wrench. One of the students exerts the
two 60-lb forces; the other, having to reach around his
friend, can only exert the two 30-lb forces. What torque
(moment) do they exert on the nut?
Problem 4.98 The tension in cable AB is 80 lb. What
is the moment about the line CD due to the force exerted
by the cable on the wall at B?
A (6, 0, 10) ft
Solution: The strategy is to nd the moment about the point C
Problem 4.163 The engine above the airplanes fuselage exerts a thrust T0 = 16 kip, and each of the engines
under the wings exerts a thrust TU = 12 kip. The dimensions are h = 8 ft, c = 12 ft, and b = 16 ft. If you
represent the three thrust forces by a fo
Process 1-2: Compression with pV = constant, W12 = -104 kJ,
U1 = 512 kJ, U2 = 690 kJ
Process 2-3: W23 = 0, Q23 = -150 kJ
Process 3-1: W31 = +
Problem 4.108 Determine the moment of the couple
and represent it as shown in Fig. 4.28(c).
10 j (N)
(4, 0, 0) m
10 j (N)
The moment of the couple is
M = r F = 4i 10j = 40k (N-m)
(4, 0, 0)
Problem 4.109 The
PROBLEM 2.78 (Continued) Page 2
Problem 2.78 (Continued) Page 2
A gas undergoes a cycle in a piston-cylinder assembly consisting of the following three
Process 1-2: Constant pressure, p = 1.4 bar, V1 = 0.028 m3, W12 =
PROBLEM 2.65 (Continued)
A gas undergoes a process in a piston-cylinder assembly during which the pressure-specific
volume relation is pv1.2 = constant. The mass of the gas is 0.4 lb and the following data are
known: p1 = 160 lbf/in.2, V1 = 1