Escape Velocity & Energy of Orbits — A/L Physics

Escape Velocity The minimum speed required for an object to escape a planet's gravitational field without further propulsion. Escape velocity is independent of the mass of the escaping object. It depends only on the mass and radius of the celestial body. For Earth, escape velocity is approximately 11.2 km/s. Intuitively, if you throw a ball upward at exactly this speed, it will never fall back—it will coast to infinity, slowing to zero speed at infinite distance.

Binding Energy The total mechanical energy (kinetic + potential) of a satellite in a stable orbit. For a satellite in a circular orbit, the binding energy is negative, indicating that the satellite is gravitationally bound to the central body. The magnitude of this energy is the work required to move the satellite to infinity (i.e., to unbind it). Mathematically, for a circular orbit, E = -(GMm)/(2r) .