Study Lagrangian Mechanics: D'Alembert's Principle

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In summary, D'Alembert's principle allows for a formulation of equations of motion without the influence of constraints. Virtual displacement, which is not a real displacement, does not contain a change in time because it is not affected by constraints. This has advantages over the traditional Newtonian description of mechanics.
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KT KIM
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Studying Lagrangian mechanics starting from D'Alembert's principle.
I just ran into this.
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Why virtual displacement doesn't contain time t for it's coordinates
What does that mean 'take place at a fixed time'?
 
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KT KIM said:
Why virtual displacement doesn't contain time t for it's coordinates

The simplest answer is that its not 'real' displacement therefore it must not contain change in time - and that's why its called 'virtual'

if a geometrical change in the configuration of the physical system is done consistent with the constraints operating on the system then one can formulate a principle which helps in weaning away the force of constrains from equation of motion. and that has certain advantage over Newtonian description.
 
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Thank you much for fine answer, helped me a lot. Guess need some time to grasp that notion well.
 

Related to Study Lagrangian Mechanics: D'Alembert's Principle

1. What is Lagrangian Mechanics?

Lagrangian Mechanics is a mathematical framework for describing the motion of particles and systems in classical mechanics. It is based on the principle of least action, which states that the path a system takes between two points in time is the one that minimizes the action integral.

2. Who developed Lagrangian Mechanics?

Lagrangian Mechanics was developed by Italian mathematician and physicist Joseph-Louis Lagrange in the late 18th century. He published his work in his book "Mécanique Analytique" in 1788.

3. What is D'Alembert's Principle?

D'Alembert's Principle, also known as the principle of virtual work, is a fundamental principle in Lagrangian Mechanics. It states that the sum of the external forces and the virtual work of the internal forces on a system is equal to the product of the mass of the system and its acceleration.

4. What is the significance of D'Alembert's Principle in Lagrangian Mechanics?

D'Alembert's Principle allows us to describe the motion of complex systems by considering the virtual work of internal forces, rather than explicitly calculating those forces. This makes the calculations much simpler and more efficient, making Lagrangian Mechanics a powerful tool in analyzing the dynamics of systems.

5. How is Lagrangian Mechanics used in modern science and engineering?

Lagrangian Mechanics has a wide range of applications in modern science and engineering, including in fields such as aerospace, robotics, and biomechanics. It is also used in the development of mathematical models and simulations in physics and engineering, allowing for more accurate predictions and designs.

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