In physics, escape velocity is the minimum speed needed for an object to "break free" from the gravitational attraction of a massive body. The escape velocity from Earth is about 40,270 km/h (25,020 mph). More particularly, escape velocity is the speed at which the sum of an object's kinetic energy and its gravitational potential energy is equal to zero. If given escape velocity, the object will move away forever from the massive body, slowing forever and approaching but never quite reaching zero speed. Once escape velocity is achieved, no further impulse need be applied for it to continue in its escape. In other words, if given escape velocity, the object will move away from the other body, continually slowing and will asymptotically approach zero speed as the object's distance approaches infinity, never to return.