# period of the Earth rotation, in seconds
T = 24*3600

# angular frequency of Earth's rotation, in radians per second
Om = 2*pi/T

# radius of the Earth, in meters
R = 6.4e6

# acceleration of gravity at the Earth surface, in m/s^2
g = 9.8

# The radius of the satelite's orbit
r0 = (g*R^2/Om^2)^(1/3)

#
rr = R/r0

# The maximal value of the tension per density
tpr = g*R*(1.0 - rr) - 1/2*Om^2*R^2*(1.0/rr^2 - 1.0)
println("required:  ", tpr)

# Tensile strength for steel, in Pa
st = 4.e6

# density of steel, in kg/m^3
rho = 8.0e3

println("available: ", st/rho)