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The three-body problem is a special case of the n-body problem, which describes how n objects move under one of the physical forces, such as gravity. These problems have a global analytical solution in the form of a convergent power series, as was proven by Karl F. Sundman for n = 3 and by Qiudong Wang for n > 3 (see n -body problem for details).
(more unsolved problems in physics) In cosmology , the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density (the small value of the cosmological constant ) and the much larger theoretical value of zero-point energy suggested by quantum field theory .
In physics, natural unit systems are measurement systems for which selected physical constants have been set to 1 through nondimensionalization of physical units.For example, the speed of light c may be set to 1, and it may then be omitted, equating mass and energy directly E = m rather than using c as a conversion factor in the typical mass–energy equivalence equation E = mc 2.
The n-body problem is an ancient, classical problem [19] of predicting the individual motions of a group of celestial objects interacting with each other gravitationally. Solving this problem – from the time of the Greeks and on – has been motivated by the desire to understand the motions of the Sun, planets and the visible stars.
In classical mechanics, the central-force problem is to determine the motion of a particle in a single central potential field.A central force is a force (possibly negative) that points from the particle directly towards a fixed point in space, the center, and whose magnitude only depends on the distance of the object to the center.
Heat capacity per unit mass J/(K⋅kg) L 2 T −2 Θ −1: intensive Specific volume: v: Volume per unit mass (reciprocal of density) m 3 ⋅kg −1: L 3 M −1: intensive Spin: S: Quantum-mechanically defined angular momentum of a particle kg⋅m 2 ⋅s −1: L 2 M T −1: Strain: ε: Extension per unit length unitless 1: Stress: σ: Force per ...
During the first 0.05 s the ball drops one unit of distance (about 12 mm), by 0.10 s it has dropped at total of 4 units, by 0.15 s 9 units, and so on. Near the surface of the Earth, the acceleration due to gravity g = 9.807 m/s 2 ( metres per second squared , which might be thought of as "metres per second, per second"; or 32.18 ft/s 2 as "feet ...
In physics, action is a scalar quantity that describes how the balance of kinetic versus potential energy of a physical system changes with trajectory. Action is significant because it is an input to the principle of stationary action , an approach to classical mechanics that is simpler for multiple objects. [ 1 ]