posted by Kyla .
How much energy is required to move a 900 kg object from the Earth's surface to an altitude twice the Earth's radius?
The potential energy increase is:
W = - M m G/(2R) + M m G/R
where M is the mass of the Earth, m is the mass of the object and R is the Earth's radius and G is the gravitational constant.
We can simplify the expression for W:
W = 1/2 M m G/R = m R/2 (M G /R^2) =
m R/2 g = 2.82*10^10 J