# Example 20-1
MKS(kJ)
e = 0.2
Wave = 23 kJ
Qh = Wave / e
Ql = (1 - e) * Qh

# Example 20-2
QL = 4 kJ
TL = 285 degK
QH = 9 kJ
TH = 435 degK
e = 1 - QL / QH
eideal = 1 - TL / TH

# Example 20-3
gam = 1.4
va_over_vb = 8
e = 1 - va_over_vb^(1 - gam)

# Example 20-4
QL = 2e5 J
COP = 3.8
W1 = 200 W
t = QL / COP / W1

# Example 20-5
MKS(J)
COP = 3
W1 = 1500 J
QH = COP * W1
QL = QH - W1
COP2 = QL / W1

# Example 20-6
MKS(J, J / degK)
m1 = 50 kg
t1 = 20 degC
m2 = 50 kg
t2 = 24 degC
cw = 4186 J / kg degC
tf = 22 degC
Q1 = m1 * cw * (t1 - tf)
Q2 = m2 * cw * (t2 - tf)
delS1 = Q1 / (0.5 * (t1 + tf))
delS2 = Q1 / (0.5 * (t2 + tf))
delS2 - delS1

# Example 20-7
MKS(J, J / degK)
n1 = 1
v2_over_v1 = 2
del_s = n1 * gas() * ln(v2_over_v1)

# Example 20-8
MKS(J, J / degK)
m1 = 2 kg
c1 = 450 J / kg degK
t1 = 880 degK
t2 = 280 degK
delS = -m1 * c1 * ln(t1 / t2)
Q = m1 * c1 * (t2 - t1)
delS = -Q / t2

# Homework Problems:

TBD