Escape Velocity

This is the initial velocity that an object would have to have if projected from the surface of a body (e.g. Earth) to reach infinity before coming to rest.

Escape velocity,

Where
v = escape velocity [ms-1]
G = universal gravitational constant = 6.67x10-11Nm2kg-2
m = mass of body from which object is projected [kg]
r = radius of body from which object is projected [m]
Note:
  • This calculation applies to a body that is projected with this initial velocity. A body that is powered in flight does not have to rely on just it's initial kinetic energy to overcome the gravitational attraction of the body from which it is escaping.

  • The direction in which the object is projected is irrelevent as the energy it loses is only dependent on the height it reaches.

The Earth's escape velocity is 11.2 km s-1 ~ 25000 mph.

See also: Earth, Gravitational Potential, Newton′s Law of Universal Gravitation, Velocity.

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Subjects: Classical Mechanics