Longman Dictionary of Contemporary English
The Collaborative International Dictionary
escape velocity \es*cape" vel*o"ci*ty\, n. (Physics) The minimum velocity at which an object must be moving in order for it to overcome the gravitational attraction of a massive celestial body, such as the earth or the sun, and escape beyond its gravitational field into free space. The velocity is calculated as though attained instantaneously at the surface of the celestial body, and is pointed directly away from its center, and neglecting effects of atmospheric friction. Rockets, which accelerate gradually and are moving rapidly at a high altitude when their fuel is exhausted or their engines shut off, may escape even if moving slightly slower at that point than the surface escape velocity. Compare orbital velocity. Note: The escape velocity at the surface of the earth is 1
2 km/sec (25,100 miles per hour), at the moon's surface is
4 km/sec, and at the sun's surface is 617.7 km/sec. The escape velocity is calculated as: Ve = root 2Rg where R is the radius of the celestial body and g is the acceleration due to the gravitational field at its surface. The peculiar chracteristic of a black hole is that the escape velocity at its ``surface'' (called its ``event horizon'') is greater than the speed of light. Therefore nothing, not even light, may escape from it.
--Dict. Sci. Tech.
Wiktionary
n. (context astrophysics English) The minimum velocity needed to escape the gravitational field of a planet or other body.
WordNet
n. the minimum velocity needed to escape a gravitational field
Wikipedia
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 at the surface. More generally, escape velocity is the speed at which the sum of an object's kinetic energy and its gravitational potential energy is equal to zero. Given escape velocity perpendicular to a massive body, the object will move away from the body, slowing forever and approaching but never 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.
For a spherically symmetric massive body such as a star or planet, the escape velocity for that body, at a given distance is calculated by the formula
$$v_e = \sqrt{\frac{2GM}{r}},$$
where G is the universal gravitational constant (G = 6.67×10 m kg s), M the mass of the body to be escaped, and r the distance from the center of mass of the mass M to the object. The relation is independent of the mass of the object escaping the mass body M. Conversely, a body that falls under the force of gravitational attraction of mass M from infinity, starting with zero velocity, will strike the mass with a velocity equal to its escape velocity.
When given a speed V greater than the escape speed v, the object will asymptotically approach the hyperbolic excess speed v, satisfying the equation:
v = V − v.
In these equations atmospheric friction ( air drag) is not taken into account. A rocket moving out of a gravity well does not actually need to attain escape velocity to escape, but could achieve the same result (escape) at any speed with a suitable mode of propulsion and sufficient propellant to provide the accelerating force on the object to escape. Escape velocity is only required to send a ballistic object on a trajectory that will allow the object to escape the gravity well of the mass M.
Escape velocity is the minimum speed an object without propulsion needs to have to move away indefinitely from the source of the gravity field.
Escape velocity may also refer to:
Escape Velocity is a BBC Books original novel written by Colin Brake and based on the long-running British science fiction television series Doctor Who. It features the Eighth Doctor and Fitz and introduces the new companion of Anji Kapoor. This book completes the story arc in which the Doctor was trapped on Earth for a hundred years.
"Escape Velocity" is the sixth episode in the fourth season of the science fiction television series Battlestar Galactica. It first aired on April 25, 2008. The survivor count shown in the title sequence is 39,675.
Escape Velocity is a 1998 Canadian thriller film, directed by Lloyd A. Simandl.
Escape Velocity is a single-player role-playing space trading and combat video game series first introduced in 1996 by Ambrosia Software for the Apple Macintosh. Two other similar games based on the original, EV Override and EV Nova, followed in 1998 and 2002 respectively, the latter of which is also available on Microsoft Windows. In addition there is a trading card game available based on the storyline of the EV Nova universe.
The series was created as a joint effort between several people and groups. Matt Burch programmed all three games in their entirety except for the registration system and various libraries. He also devised and created the scenario for the first game. Ambrosia Software, headed by Andrew Welch, managed marketing, registration, and distribution, as well as providing several external libraries used by the games. Early test versions of the game went by the name 'Merc' (short for ' mercenary'). Peter Cartwright wrote the scenario for EV Override and the Australian company ATMOS created the scenario of EV Nova; both originated as plug-ins for the preceding games before being picked up by Ambrosia as sequels. The fighter pilot voices in the original game were provided by Patrick Delahanty. A plug-in of additional phrases was also created and later included as part of EV Override.
While there have been no announcements regarding the future of the series since the 2002 release of Escape Velocity Nova, the extensible plug-in system allows users to continue developing new third-party content for the game. Additionally, several community projects have arisen to build spiritual successors to the series, of which NAEV is one of the better-known.
"Escape Velocity" is a song by The Chemical Brothers, released as a white label promotional single from their 2010 album Further. The version that appears on the single is different from that found on the album, in that it features no transition out of "Snow" or into "Another World."
The song was broadcast in part on Pete Tong's radio show on BBC Radio 1. It was also played before its release in a Chemical Brothers DJ set at Coachella 2009, along with "Don't Think," which was ultimately released as a bonus track on the iTunes edition of Further. It was also used in the videogame Gran Turismo 5.
Usage examples of "escape velocity".
Now I must maintain the balance, far enough from the Star to avoid destruction by radiation, far enough from the Hole to retain escape velocity.
The biggest advantage of the Moon may turn out to be its low escape velocity, only 2.
For that matter our cruising velocity would have been well beyond escape velocity on Earth.
But Jupiter's escape velocity is quintuple that of Earth's, so we were in no danger of flying free.
I used to wonder how the escape velocity could be quintuple when the gee was only two and a half times Earth's, until I realized that the total size of Jupiter's gravity well is much larger than Earth's.
Tiny bits, carried away from the surface in the waning blow of escaping gas, had never quite reached escape velocity, even from the comet’.
Discovery was moving at a little more than Earth's escape velocity, seven miles a second.
Next, we have to accelerate to escape velocity and get clear of the planet.
I used to wonder how the escape velocity could be quintuple when the gee was only two and a half times Earth’.
I fear you could achieve escape velocity if you really tried, and that would be awkward indeed.
There followed a rapid-fire listing of temperatures in Kelvin, atmospheric pressure in millibars, estimated mean density in grams per centimeter cubed, probable escape velocity in kilometers per second, and perceived magnetic field in gauss, followed by a long list of atmospheric gases and element ratios.
A photon traveling at the speed of light away from the star is constrained to follow a curved path and fall back upon the star, just as the Earth's gravity is too strong for any of us to throw a rock to escape velocity.