Re: Escape Velocity Equation

Remember that the "critical" velocity is the velocity that a
near-earth satellite needs to stay in orbit.  That velocity,
as you can find in any physics textbook, is
   critical v = sqrt( GM / R )
where G is the gravitational constant,
      M is the mass of the earth, and
      R is the radius of the satellite's orbit, assumed
to be close enough to the surface that R is almost the
radius of the earth.

For the escape velocity, that velocity needed for an object
to escape from the surface of the earth, the formula is
   escape v = sqrt( 2GM / R )
and so the ratio
   escape v / critical v = sqrt( 2 )
which is approximately 1.4