# Example 9-1
MKS(N)
v1 = 55 m / s
m1 = 60 g
f1 = m1 * grav()
t1 = 4 ms
f_bar = m1 * v1 / t1
m2 = 60 kg
f2 = m2 * grav()

# Example 9-2
MKS(N)
p_final = 0
p_init = (1 s) * (1.5 kg) * (20 m/s)
f = (p_final - p_init) / (1 s)

# Example 9-3
ma = 10000 kg
mb = 10000 kg
va = 24 m/s
v = ma * va / (ma + mb)

# Example 9-4
mb = 20 g
vb = 620 m/s
mr = 5 kg
vr = - mb * vb / mr

# Example 9-6
MKS(kN)
m1 = 1 kg
v1 = 10 m/s
p1 = m1 * v1
x2  = 1 cm
v2 = 5 m/s
t2 = x2 / v2
f2 = p1 /t2

# Example 9-9
u = 1.66e-27 kg
mp = 1.01 * u
vp = 3.60e4 m/s
mhe = 4 * u
vhe = 2 * mp * vp / (mp + mhe)
v = vhe - vp

# Example 9-10
MKS(MJ)
ma = 10000 kg
va = 24 m/s
ua = 0.5 * ma * va^2
mb = 20000 kg
vb = 12 m/s
ub = 0.5 * mb * vb^2
del_u = ua - ub

# Example 9-12
va = 3 m/s
va_prime = va / (2 * cos(45 deg))

# Example 9-13
va = 4.1e5 m/s
vb = 7.1e5 m/s
qa = 60 deg
qb = asin(-sin(qa) * va/ vb); deg

# Example 9-14
xa = 1 m
xb = 5 m
xc = 6 m
xcm = (xa + xb + xc) / 3

# Example 9-15
x1 = [0, 0] m
x2 = [2, 0] m
x3 = [2, 1.5] m
xcm = (x1 + x2 + x3) / 3

# Example 9-17
x1 = [1.03, 0.1] m
x2 = [1.96, -0.74] m
m1 = 2.06 * 0.2
m2 = 1.48 * 0.2
xcm = (m1 * x1  + m2 * x2) / (m1 + m2)

# Example 9-19
MKS(N)
v = 2.2 m/s
dm_dt = 75 kg/s
f = v * dm_dt

# Example 9-20
MKS(N)
v = -2800 m/s
dm_dt = -190 kg/s
f_thrust = v * dm_dt
m1 = 2.1e4 kg
f1 = m1 * grav()
m2 = 6e3 kg
f2 = m2 * grav()
fnet1 = f_thrust - f1
fnet2 = f_thrust - f2
del_m = -1.5e4 kg
del_t = del_m / dm_dt
v = -grav() * del_t + v * log(m2 / m1)

# Homework Problems:

TBD