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  2. Free-fall time - Wikipedia

    en.wikipedia.org/wiki/Free-fall_time

    The free-fall time is the characteristic time that would take a body to collapse under its own gravitational attraction, if no other forces existed to oppose the collapse.. As such, it plays a fundamental role in setting the timescale for a wide variety of astrophysical processes—from star formation to helioseismology to supernovae—in which gravity plays a dominant ro

  3. Equations for a falling body - Wikipedia

    en.wikipedia.org/wiki/Equations_for_a_falling_body

    Based on wind resistance, for example, the terminal velocity of a skydiver in a belly-to-earth (i.e., face down) free-fall position is about 195 km/h (122 mph or 54 m/s). [3] This velocity is the asymptotic limiting value of the acceleration process, because the effective forces on the body balance each other more and more closely as the ...

  4. Free fall - Wikipedia

    en.wikipedia.org/wiki/Free_fall

    The experimental observation that all objects in free fall accelerate at the same rate, as noted by Galileo and then embodied in Newton's theory as the equality of gravitational and inertial masses, and later confirmed to high accuracy by modern forms of the Eötvös experiment, is the basis of the equivalence principle, from which basis ...

  5. Terminal velocity - Wikipedia

    en.wikipedia.org/wiki/Terminal_velocity

    Based on air resistance, for example, the terminal speed of a skydiver in a belly-to-earth (i.e., face down) free fall position is about 55 m/s (180 ft/s). [3] This speed is the asymptotic limiting value of the speed, and the forces acting on the body balance each other more and more closely as the terminal speed is approached.

  6. Jeans instability - Wikipedia

    en.wikipedia.org/wiki/Jeans_instability

    At the same time, gravity will attempt to contract the system even further, and will do so on a free-fall time = / /, where is the universal gravitational constant, is the gas density within the region, and = / is the gas number density for mean mass per particle (μ = 3.9 × 10 −24 g is appropriate for molecular hydrogen with 20% helium by ...

  7. Geodesics in general relativity - Wikipedia

    en.wikipedia.org/wiki/Geodesics_in_general...

    These last three equations can be used as the starting point for the derivation of an equation of motion in General Relativity, instead of assuming that acceleration is zero in free fall. [2] Because the Minkowski tensor is involved here, it becomes necessary to introduce something called the metric tensor in General Relativity.

  8. Brachistochrone curve - Wikipedia

    en.wikipedia.org/wiki/Brachistochrone_curve

    The curve of fastest descent is not a straight or polygonal line (blue) but a cycloid (red).. In physics and mathematics, a brachistochrone curve (from Ancient Greek βράχιστος χρόνος (brákhistos khrónos) 'shortest time'), [1] or curve of fastest descent, is the one lying on the plane between a point A and a lower point B, where B is not directly below A, on which a bead slides ...

  9. List of relativistic equations - Wikipedia

    en.wikipedia.org/wiki/List_of_relativistic_equations

    Also, the velocities in the directions perpendicular to the frame changes are affected, as shown above. This is due to time dilation, as encapsulated in the dt/dt′ transformation. The V′ y and V′ z equations were both derived by dividing the appropriate space differential (e.g. dy′ or dz′) by the time differential.