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Integration of an absorption coefficient over a path from s 1 and s 2 affords the optical thickness (τ) of that path, a dimensionless quantity that is used in some variants of the Schwarzschild equation. When emission is ignored, the incoming radiation is reduced by a factor for 1/e when transmitted over a path with an optical thickness of 1.
For a particle whose velocity is small relative to the speed of light (i.e., nonrelativistic), the total power that the particle radiates (when considered as a point charge) can be calculated by the Larmor formula: = (˙) = = = = where ˙ or is the proper acceleration, is the charge, and is the speed of light. [2]
In general relativity, a congruence (more properly, a congruence of curves) is the set of integral curves of a (nowhere vanishing) vector field in a four-dimensional Lorentzian manifold which is interpreted physically as a model of spacetime. Often this manifold will be taken to be an exact or approximate solution to the Einstein field equation.
For any curve and two points = and = on this curve, an affine connection gives rise to a map of vectors in the tangent space at into vectors in the tangent space at : =,, and () can be computed component-wise by solving the differential equation = () = () where () is the vector tangent to the curve at the point ().
Relative velocities between two particles in classical mechanics. The figure shows two objects A and B moving at constant velocity. The equations of motion are: = +, = +, where the subscript i refers to the initial displacement (at time t equal to zero).
There are two main descriptions of motion: dynamics and kinematics.Dynamics is general, since the momenta, forces and energy of the particles are taken into account. In this instance, sometimes the term dynamics refers to the differential equations that the system satisfies (e.g., Newton's second law or Euler–Lagrange equations), and sometimes to the solutions to those equations.
Winter brings less daylight and colder temperatures, which can disrupt sleep. Seasonal Affective Disorder (SAD) is more common in winter due to the lack of sunlight, causing sleep disturbances.
Diffusion cloud chamber with tracks of ionizing radiation (alpha particles) that are made visible as strings of droplets. In dosimetry, linear energy transfer (LET) is the amount of energy that an ionizing particle transfers to the material traversed per unit distance.