势头
... impetus 推动力 momentum 势头 push 推 ...
动量
... moment 力矩,矩,动差 momentum 动量 momentum transfer 动量传递 ...
物 角动量 ; 动量矩 ; 影格拉 ; 安格蒙特
动量算符 ; 力 动量算子 ; 角动量算符
四维动量
In classical mechanics, linear momentum or translational momentum (pl. momenta; SI unit kg m/s, or equivalently, N s) is the product of the mass and velocity of an object. For example, a heavy truck moving rapidly has a large momentum—it takes a large or prolonged force to get the truck up to this speed, and it takes a large or prolonged force to bring it to a stop afterwards. If the truck were lighter, or moving more slowly, then it would have less momentum.Like velocity, linear momentum is a vector quantity, possessing a direction as well as a magnitude:Linear momentum is also a conserved quantity, meaning that if a closed system is not affected by external forces, its total linear momentum cannot change. In classical mechanics, conservation of linear momentum is implied by Newton's laws; but it also holds in special relativity (with a modified formula) and, with appropriate definitions, a (generalized) linear momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory, and general relativity.