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# 14: Hamiltonian Mechanics

[ "article:topic-guide", "authorname:tatumj", "Hamiltonian Mechanics" ]

Hamiltonian mechanics can be used to describe simple systems such as a bouncing ball, a pendulum or an oscillating spring in which energy changes from kinetic to potential and back again over time, its strength is shown in more complex dynamic systems, such as planetary orbits in celestial mechanics. The more degrees of freedom the system has, the more complicated its time evolution.

• 14.1: Introduction to Hamiltonian Mechanics
Hamilton theory – or more particularly its extension the Hamilton-Jacobi equations - does have applications in celestial mechanics, and of course hamiltonian operators play a major part in quantum mechanics, although it is doubtful whether Sir William would have recognized his authorship in that connection.
• 14.2: A Thermodynamics Analogy
Readers may have noticed from time to time – particularly in Chapter 9 - that I have perceived some connection between parts of classical mechanics and thermodynamics. I perceive such an analogy in developing hamiltonian dynamics. Those who are familiar with thermodynamics may also recognize the analogy.
• 14.3: Hamilton's Equations of Motion
In classical mechanics we can describe the state of a system by specifying its Lagrangian as a function of the coordinates and their time rates of change.However, it is sometimes convenient to change the basis of the description of the state of a system by defining a quantity called the hamiltonian H.
• 14.4: Hamiltonian Mechanics Examples
I’ll do two examples by hamiltonian methods – the simple harmonic oscillator and the soap slithering in a conical basin. Both are conservative systems, and we can write the hamiltonian as T+V , but we need to remember that we are regarding the hamiltonian as a function of the generalized coordinates and momenta.
• 14.5: Poisson Brackets
The Poisson bracket is an important binary operation in Hamiltonian mechanics, playing a central role in Hamilton's equations of motion, which govern the time evolution of a Hamiltonian dynamical system.

Thumbnail: The time evolution of the system is uniquely defined by Hamilton's equations where H = H(q, p, t) is the Hamiltonian, which often corresponds to the total energy of the system. For a closed system, it is the sum of the kinetic and potential energy in the system.