Abstract:
Today, many branches of science are into our lives. One the branches is
mathematics that has multiple applications. In particular , differential geometry and
mathematical physics have a lots of different applications. One of them are on
geodesics. Geodesics are known the shortest route between two points. Time-dependent
equations of geodesics can be easily found with the help of the Euler-Lagrange
equations. We can say that differential geometry provides a good working area for
studying Lagrangians of classical mechanics and field theory. The dynamic equation for
moving bodies is obtained for Lagrangian mechanic. These dynamic equation is
illustrated as follows:
Lagrange Dynamics Equation [1,2,3]: let M be an n-dimensional manifold and TM its
tangent bundle with canonical projection 𝑇𝑇𝑇𝑇: 𝑇𝑇𝑇𝑇 β 𝑀𝑀 is called the phase space of
velocities of the base manifold M.
Let 𝐿𝐿: 𝑇𝑇𝑇𝑇 β 𝑅𝑅 be differentiable function on TM called the Lagrangian function.
We consider the closed 2-form on TM given by Ξ¦𝐿𝐿 = 𝑑𝑑𝑑𝑑𝐽𝐽𝐿𝐿 ( if 𝐽𝐽2 = β𝐼𝐼 ,𝐽𝐽 is a complex
structure and if 𝐽𝐽2 = 𝐼𝐼 ,𝐽𝐽 is a paracomplex structures, 𝑇𝑇𝑟𝑟 (𝐽𝐽) = 0) Consider the equation:
𝑖𝑖𝑋𝑋Ξ¦𝐿𝐿 = 𝑑𝑑𝐸𝐸𝐿𝐿
β
Then 𝑋𝑋 is a vector field, we shall see that (1) under a certain condition on 𝑋𝑋 is
the intrinsical expression of the Euler-Lagrange equations of motion. This equation is
named as Lagrange dynamical equation. We shall see that for motion in potential,
𝐸𝐸𝐿𝐿 = 𝑉𝑉(𝐿𝐿) β 𝐿𝐿 is an energy function and 𝑉𝑉 = 𝐽𝐽(𝑋𝑋) a Liouville vector field. Here 𝑑𝑑𝐸𝐸𝐿𝐿
denotes the differential of 𝐸𝐸. The triple (𝑇𝑇𝑇𝑇, Ξ¦𝐿𝐿, 𝑋𝑋) is known as Lagrangian system on