Answer to Question #148330 in Classical Mechanics for Alfraid

Question

What is unit of action.

Answer 1

In physics, action is an attribute of the dynamics of a physical system from which the equations of motion of the system can be derived through the principle of stationary action. Action is a mathematical functional which takes the trajectory, also called path or history, of the system as its argument and has a real number as its result. Generally, the action takes different values for different paths.

Action has dimensions of [energy]⋅[time] or [momentum]⋅[length], and its SI unit is joule-second. Action is only of interest when the total energy of the system is conserved.