Lagrangian: kinetic matrix Z_ij and mass matrix k_ij

  • #1
GGGGc
Screen Shot 2023-10-04 at 08.43.45.png

Can somebody explain why the kinetic term for the fluctuations was already diagonal and why to normalize it, the sqrt(m) is added? Any why here Z_ij = delta_ij?
Quite confused about understanding this paragraph, can anybody explain it more easily?
 
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  • #2
How can we answer this question, without knowing, what the example actually is? It's also mandatory to quote the textbook/paper you picture is taken from.
 

What is the Lagrangian kinetic matrix Z_ij?

The Lagrangian kinetic matrix Z_ij represents the kinetic energy of a system in terms of generalized coordinates. It is a square matrix where each element Z_ij corresponds to the coefficient of the product of the generalized velocities q_i_dot and q_j_dot in the kinetic energy expression.

What is the mass matrix k_ij in Lagrangian dynamics?

The mass matrix k_ij in Lagrangian dynamics represents the inertia of a system with respect to the generalized coordinates. It is a square matrix where each element k_ij corresponds to the coefficient of the product of the generalized accelerations q_i_double_dot and q_j_double_dot in the Lagrangian equation.

How are the Lagrangian kinetic matrix Z_ij and mass matrix k_ij related?

The Lagrangian kinetic matrix Z_ij and mass matrix k_ij are related through the kinetic energy expression of a system. The Lagrangian kinetic matrix Z_ij is used to define the kinetic energy of the system, while the mass matrix k_ij is used to define the inertia of the system. Together, they form the basis for solving the equations of motion in Lagrangian dynamics.

How are the Lagrangian kinetic matrix Z_ij and mass matrix k_ij calculated?

The Lagrangian kinetic matrix Z_ij and mass matrix k_ij are calculated by differentiating the kinetic energy expression of the system with respect to the generalized velocities and accelerations, respectively. The elements of these matrices are obtained by taking partial derivatives of the kinetic energy expression with respect to the corresponding generalized coordinates.

Why are the Lagrangian kinetic matrix Z_ij and mass matrix k_ij important in Lagrangian dynamics?

The Lagrangian kinetic matrix Z_ij and mass matrix k_ij play a crucial role in formulating and solving the equations of motion in Lagrangian dynamics. They provide a systematic way to analyze the dynamics of complex mechanical systems and derive the equations of motion using the principle of least action. By understanding and manipulating these matrices, scientists and engineers can predict the behavior of systems and design control strategies for optimal performance.

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