To project a body of mass m from earth's surface to infinity, the required kinetic energy is (assume, the radius of earth is Rₑ, g = acceleration due to gravity on the surface of earth) :
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To project a body of mass m from earth's surface to infinity, the required kinetic energy is (assume, the radius of earth is Rₑ, g = acceleration due to gravity on the surface of earth) :

G1 Physics · Accepted Answer

Minimum required kinetic energy equals the magnitude of gravitational potential energy at Earth's surface: K = GMm/Rₑ Using: g = GM/Rₑ² we get: GM = gRₑ² Therefore: K = mgRₑ