shirabe.org
Meaning
  1. 1
    English · JMdict
    escape velocity;orbital velocity;cosmic speed;space velocity
  2. 2
    English · Wikipedia

    In physics, escape velocity is the minimum speed needed for an object to escape from the gravitational attraction of a massive body, without the aid of thrust, or suffering the resistance from friction. The escape velocity from Earth is about 11.186 km/s (40,270 km/h; 25,020 mph) 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 where G is the universal gravitational constant (G = 6.67×10−11 m3 kg−1 s−2), M the mass of the body to be escaped, and r the distance from the center of mass of the body 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 greater than the escape speed the object will asymptotically approach the hyperbolic excess speed satisfying the equation: 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.

    Read full article on Wikipedia · CC-BY-SA

Save this word to start reviewing it with spaced repetition. Save word

Grammar codex

What the coloured tags mean

Hiragana

ひらがな

The rounded, flowing kana. Hiragana writes native Japanese words, grammar endings, and anything without (or alongside) kanji — it's the first script you learn. Each character stands for one syllable.

Example

ねこ — cat