# Physics

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How much energy is required to move a 900 kg object from the Earth's surface to an altitude twice the Earth's radius?

• Physics -

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

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