Escape Velocity (Paperback)

In physics, escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy, as calculated by the equation, It is commonly described as the speed needed to "break free" from a gravitational field (without any additional impulse) and is theoretical, totally neglecting atmospheric friction. The term escape velocity can be considered a misnomer because it is actually a speed rather than a velocity, i.e. it specifies how fast the object must move but the direction of movement is irrelevant, unless "downward." In more technical terms, escape velocity is a scalar (and not a vector). Escape velocity gives a minimum delta-v budget for rockets when no benefit can be obtained from the speeds of other bodies for a particular mission; but it neglects losses such as air drag and gravity drag. However in some cases it can be improved upon, for example, by use of gravitational slingshots.