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  2. Escape velocity - Wikipedia

    en.wikipedia.org/wiki/Escape_velocity

    An alternative expression for the escape velocity v e particularly useful at the surface on the body is: = where r is the distance between the center of the body and the point at which escape velocity is being calculated and g is the gravitational acceleration at that distance (i.e., the surface gravity). [11]

  3. Event horizon - Wikipedia

    en.wikipedia.org/wiki/Event_horizon

    One of the best-known examples of an event horizon derives from general relativity's description of a black hole, a celestial object so dense that no nearby matter or radiation can escape its gravitational field. Often, this is described as the boundary within which the black hole's escape velocity is greater than the speed of light.

  4. Delta-v - Wikipedia

    en.wikipedia.org/wiki/Delta-v

    Delta-v (also known as "change in velocity"), symbolized as and pronounced /dɛltə viː/, as used in spacecraft flight dynamics, is a measure of the impulse per unit of spacecraft mass that is needed to perform a maneuver such as launching from or landing on a planet or moon, or an in-space orbital maneuver.

  5. Glossary of physics - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_physics

    A branch of physics that studies atoms as isolated systems of electrons and an atomic nucleus. Compare nuclear physics. atomic structure atomic weight (A) The sum total of protons (or electrons) and neutrons within an atom. audio frequency A periodic vibration whose frequency is in the band audible to the average human, the human hearing range.

  6. Longevity escape velocity - Wikipedia

    en.wikipedia.org/wiki/Longevity_escape_velocity

    "The first 1000-year-old is probably only ~10 years younger than the first 150-year-old."–Aubrey de Grey, 2005 [1]. In the life extension movement, longevity escape velocity (LEV), actuarial escape velocity [2] or biological escape velocity [3] is a hypothetical situation in which one's remaining life expectancy (not life expectancy at birth) is extended longer than the time that is passing.

  7. Atmospheric escape - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_escape

    One classical thermal escape mechanism is Jeans escape, [1] named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. [2] In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy.

  8. List of common physics notations - Wikipedia

    en.wikipedia.org/wiki/List_of_common_physics...

    Meaning SI unit of measure alpha: alpha particle: angular acceleration: radian per second squared (rad/s 2) fine-structure constant: unitless beta: velocity in terms of the speed of light c: unitless beta particle: gamma: Lorentz factor: unitless photon: gamma ray: shear strain: radian

  9. Characteristic energy - Wikipedia

    en.wikipedia.org/wiki/Characteristic_energy

    In astrodynamics, the characteristic energy is a measure of the excess specific energy over that required to just barely escape from a massive body. The units are length 2 time −2, i.e. velocity squared, or energy per mass.