Velocity quantity, momentum, is a vector and defined by In special relativity, the dimensionless Lorentz factor appears frequently, and is given by where γ is the Lorentz factor and "c" is the speed of light. Escape velocity is the minimum speed a ballistic object needs to escape from a massive body such as Earth. It represents the kinetic energy that, when added to the object's gravitational potential energy, (which is always negative) is equal to zero. The general formula for the escape velocity of an object at a distance "r" from the center of a planet with mass "M" is where
Mode of a linear field usually the energy of the solution "assuming that there is no other field in S". From the norm are defined the orthogonality and the scalar product of solutions. The orthogonality of solutions extends to the corresponding modes. Mode of a linear field In physics, a vector field is linear if it is a solution of a set of linear equations "E". For instance, in physics, the electromagnetic field in vacuum, defined in the usual (3 + 1)-dimensional space "S", obeys Maxwell's equations. A linear combination of electromagnetic fields, with constant, real coefficients, is a new field which obeys Maxwell's equations.