# Tag: action

## classical mechanics – Why the Principle of Least Action?

The Question : 95 people think this question is useful I’ll be generous and say it might be reasonable to assume that nature would tend to minimize, or maybe even maximize, the integral over time of $T-V$. Okay, fine. You write down the action functional, require that it be a minimum (or maximum), and arrive

## variational principle – Why are there only derivatives to the first order in the Lagrangian?

The Question : 122 people think this question is useful Why is the Lagrangian a function of the position and velocity (possibly also of time) and why are dependences on higher order derivatives (acceleration, jerk,…) excluded? Is there a good reason for this or is it simply “because it works”. The Question Comments : The