Practice Questions (Lagrangians + Hamiltonians)

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In summary, a Lagrangian is a mathematical function that describes the dynamics of a physical system in classical mechanics by taking into account its kinetic and potential energies. It is different from a Hamiltonian, which only considers the system's kinetic energy. Both functions are used in physics to predict a system's behavior and understand its conservation laws and symmetries. The principle of least action states that a system will follow a path that minimizes the action, and Lagrangians and Hamiltonians are also used in quantum mechanics to describe the behavior of quantum systems.
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Radarithm
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I need to brush up on [itex]L[/itex] and [itex]H[/itex]. Does anyone know of any sources of practice for these two? Any problem sets?

Thanks.
 
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Radarithm said:
I need to brush up on [itex]L[/itex] and [itex]H[/itex]. Does anyone know of any sources of practice for these two? Any problem sets?

Thanks.
Look for the Schaum's Outline of Theoretical Mechanics.
 
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clope023 said:
Look for the Schaum's Outline of Theoretical Mechanics.
Looks good. Thanks.
 

1. What is a Lagrangian?

A Lagrangian is a mathematical function used in classical mechanics to describe the dynamics of a physical system. It takes into account the kinetic and potential energies of the system and allows for the calculation of the system's equations of motion.

2. How is a Lagrangian different from a Hamiltonian?

A Hamiltonian is also a mathematical function used in classical mechanics to describe the dynamics of a physical system. However, it takes into account only the system's kinetic energy and not its potential energy. In some cases, the two functions can be related through a mathematical transformation, but they are fundamentally different.

3. Why are Lagrangians and Hamiltonians used in physics?

Lagrangians and Hamiltonians are used in physics because they provide a powerful and elegant way to describe the behavior of a physical system. They allow for the calculation of a system's equations of motion, which can then be used to predict the future behavior of the system. They also provide a framework for understanding conservation laws and symmetries in a system.

4. What is the principle of least action?

The principle of least action, also known as the principle of stationary action, is a fundamental concept in classical mechanics that states that a physical system will follow a path that minimizes the action, which is the integral of the Lagrangian over time. In other words, the system will follow the path of least resistance or the path that requires the least amount of energy to travel.

5. How are Lagrangians and Hamiltonians used in quantum mechanics?

In quantum mechanics, Lagrangians and Hamiltonians are used to describe the behavior of quantum systems. However, in this context, they are represented by operators rather than functions and are used to calculate the system's wavefunction and its evolution over time. This allows for the prediction of a system's behavior on a microscopic scale.

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