# Example 6.1
1 ft lb / s ; W


# Example 6.2
MKS(N, N m)
E = 210 GPa
len = 325 mm
a = 7.854e-5 m^2
k = E * a / len
del_len = 7.882e-5 m
U = 0.5 * k * del_len^2; J


# Example 6.3
w = 350000 lb
v = 400 mph
mass = w / grav()
U = 0.5 * mass * v^2; ft lb; J

# Example 6.4
w = 3000 lbf
h = 50 ft
t = 20 s
work = w * h
power = work / t; hp

# Example 6.5
q = 98e6 btu 
h = 12.9e3 btu / lbm
mass = q / h; ton

# Example 6.6
p = 50 kW
t = 1 hr
h = 45 MJ / kg
rho = 680 kg/m^3
work = p * t; kJ
mass = work / h
vol = mass / rho; gal


# Example 6.7
d = 8 mm
a = pi() * d^2 / 4
len = 15 cm
vol = a * len
rho = 76e3 N / m^3
w = rho * vol
mass = w / grav()
c = 0.5 kJ / degC kg
t1 = 850 degC
t0 = 600 degC
q1 = mass * c * (t1 - t0); kJ
t2 = 20 degC
q2 = mass * c * (t0 - t2); kJ

# Example 6.8
a = 3ft * 4 ft
h = (1/8) in
delT = 3 degFdiff
k = 0.5 btu / hr ft degF
t = 1 hr
q = k * a * t * delT / h; J


# Example 6.9
h = 100 m
q = 500 m^3 / s
t = 1 s
rho = 1000 kg / m^3
mass = q * t * rho
u = mass * grav() * h; MJ
p_ave = u / t; MW

# Example 6.10
mass = 1200 kg
m_brake = 7 kg
v = 100 kph
f = 0.75
t1 = 25 degC
c = 0.43 kJ / degC kg
u = (1/2) * mass * v^2; kJ
q_front = f * u; kJ
t_new =  q_front / (2 * m_brake * c) + t1; degC


# Example 6.11
MKS(J)
t1 = 1 s
u = 0.9 kJ
a = 1 m^2
eff = 0.26
a_mirror = 12 m^2
p = 3 MW
t2 = 24 hr
Temp1 = 25 degC
Temp2 = 400 degC
w = p * t1
q_needed = w / eff
a_needed = q_needed / (u / a)
n = a_needed / a_mirror
eff2 = 1 - (Temp1 / Temp2)


# Example 6.12
p = 1 GW
f = 0.01
eff_scrub = 0.96
eff_power = 0.32
t1 = 1 day
h = 30 MJ/kg
w = p * t1; GJ
q = w / eff_power; GJ
m_coal = q / h
m_sulfur = f * (1 - eff_scrub) * m_coal

# Homework Problems:

TBD