# Advanced Classical Mechanics/Hamilton's Equations

## Hamilton's Equations

[edit | edit source]Hamilton's equations are an alternative to the Euler-Lagrange equations to find the equations of motion of a system. They are applied to the Hamiltonian function of the system. Hamilton's equations are

Where is the Hamiltonian, are the generalized coordinates, are the generalized momenta, and a dot represents the total time derivative. The Hamiltonian can be found by performing a Legendre transformation on the Lagrangian of the system:

where the Einstein summation notation is used, a dot represents the total time derivative, q_{i} are the generalized coordinates, p_{i} are the generalized momenta.

These momenta are found by differentiating the Lagrangian with respect to the generalized velocities . Mathematically

.

In some cases, is the total energy of the system. There are two conditions for this. First, the equations defining the generalized coordinates q don't depend on time explicitly. Second, the forces involved in the system are derivable from a scalar potential. The forces must be conservative (such as gravity).^{[1]}

References:

- ↑ Goldstein, Poole, Safko. Classical Mechanics 3rd ed. 2002