Escape velocity: -The minimum speed with which a body must be projected in order that it will escape from the earth gravitational filed is called as escape velocity.Expression of it:-consider a body of mass \\\\(m\\\\) on the surface of earthwhose mass and radius are respectively represented by \\\\(M\\\\) and \\\\(R\\\\).and earth is \\\\(F = \\dfrac{{GMm}}{{{R^2}}}\\\\)gravity potential energy \\\\(\\left( {GPE} \\right) = \\dfrac{{GMm}}{{{R^2}}}\\\\)\\\\(w = F.S = \\dfrac{{GMm}}{{{R^2}}}\\\\)In order to projector body into the space overcoming the earth's gravitational field it must be give a kinetic energy which is equal topotential energy.therefore;kinetic energy is equal to potential energy.