<Li> Newton's laws of motion </Li> <Li> Analytical mechanics <Ul> <Li> Lagrangian mechanics </Li> <Li> Hamiltonian mechanics </Li> <Li> Routhian mechanics </Li> <Li> Hamilton--Jacobi equation </Li> <Li> Appell's equation of motion </Li> <Li> Udwadia--Kalaba equation </Li> <Li> Koopman--von Neumann mechanics </Li> </Ul> </Li> <Ul> <Li> Lagrangian mechanics </Li> <Li> Hamiltonian mechanics </Li> <Li> Routhian mechanics </Li> <Li> Hamilton--Jacobi equation </Li> <Li> Appell's equation of motion </Li> <Li> Udwadia--Kalaba equation </Li> <Li> Koopman--von Neumann mechanics </Li> </Ul> <Li> Hamilton--Jacobi equation </Li>

Where does the ultimate source of energy come from