Escape speed
Escape velocity is the speed at which an object (like a rocket) has to travel to completely overcome a planet or moon's gravity and make it into space away from that planet or moon. Escape velocity is the speed that an object needs to be traveling to break free of a planet or moon's gravity well and leave it without further propulsion. For example, a spacecraft leaving the surface of Earth needs to be going 7 miles per second, or nearly 25,000 miles per hour to leave without falling back to the surface or falling into orbit.if the kinetic energy of an object launched from the Earth were equal in magnitude to the potential energy, then in the absence of friction resistance it could escape from the Earth
1/2 mv2 = GMm/RWhere m is the mass of the object, M mass of the earth, G is the gravitational constant, R is the radius of the earth, and v is the escape velocity. It simplifies to:
v = sqrt(2GM/R)