Calculating Rod Movement with Lagrangian Mechanics: Shear Modulus & Mass Ratios

In summary, the conversation is about calculating the movement of a rod/cantilever with a heavy block attached to it. The problem is understanding how the force from the block is transferred to the rod and how to incorporate the Shear modulus of the material into the equation. The speaker is seeking help with this problem and references to any helpful resources.
  • #1
danesh
6
0
Hi!
I want to calculate the movement of the rod in the picture, but I don't know how to put up the Lagrangian for the problem.
I have the Shear modulus, [tex]\mu[/tex], for the material and M>>m and [tex]\theta = 0[/tex]. I need the Lagrangian and from there on I think I can manage with the calculations myself.

Thanks
 

Attachments

  • rod.jpg
    rod.jpg
    4.6 KB · Views: 479
Physics news on Phys.org
  • #2
Can you post the wording of the problem.
 
  • #3
Gamma said:
Can you post the wording of the problem.
Well, I have come up with the problem myself.
What I am trying to get is an equation for the motion of the rod, or cantilever if you will. My problem is that I am not sure how to relate the force influencing the heavy block the rod is attached to, to the rod.
I think I need to make a connection between the Shear modulus, or the elasticity modulus of the material the rod and the block is made of to the force which is transferred to the rod.

I will settle for some help using usal mechanics on how the force is transferred from the block to the rod.

Thanks
 
  • #4
Ok, let me refrase my question a bit.
Can somebody tell me how the rod goes about to "sway" when a impulse is applied on the bigger block with mass M?
If you know a book or a homepage, which you could refer me to for this problem, I would apperciate that as well.
 

Related to Calculating Rod Movement with Lagrangian Mechanics: Shear Modulus & Mass Ratios

1. How is the shear modulus calculated in Lagrangian mechanics?

The shear modulus, also known as the modulus of rigidity, is calculated by taking the ratio of shear stress to shear strain. In Lagrangian mechanics, this can be done by using the equation: G = τ/γ, where G is the shear modulus, τ is the shear stress, and γ is the shear strain.

2. What is the role of mass ratios in calculating rod movement with Lagrangian mechanics?

Mass ratios play a crucial role in determining the movement of a rod in Lagrangian mechanics. They are used to calculate the kinetic energy of the rod, which is necessary for determining its movement. The mass ratios also affect the moment of inertia, which is used in the Lagrangian equation to determine the rod's motion.

3. What are the advantages of using Lagrangian mechanics to calculate rod movement?

Lagrangian mechanics offers several advantages over other methods of calculating rod movement. It is a more general approach that can be applied to a wide range of systems, including complex systems with multiple moving parts. It also takes into account the kinetic and potential energies of the system, providing a more comprehensive understanding of the rod's movement.

4. How does Lagrangian mechanics differ from Newtonian mechanics?

Lagrangian mechanics differs from Newtonian mechanics in several ways. While Newtonian mechanics focuses on forces and accelerations, Lagrangian mechanics focuses on energy and its conservation. Additionally, Lagrangian mechanics uses generalized coordinates to describe the system, making it more versatile and applicable to a wider range of systems.

5. Can Lagrangian mechanics be used to calculate the movement of a rod in a non-uniform gravitational field?

Yes, Lagrangian mechanics can be used to calculate the movement of a rod in a non-uniform gravitational field. The Lagrangian equation takes into account the potential energy due to gravity, so as long as the gravitational field is known, it can be incorporated into the calculations. This makes Lagrangian mechanics a powerful tool for analyzing systems in varying environments.

Similar threads

  • Introductory Physics Homework Help
Replies
7
Views
246
  • Introductory Physics Homework Help
Replies
6
Views
3K
  • Introductory Physics Homework Help
Replies
1
Views
1K
Replies
2
Views
232
  • Introductory Physics Homework Help
Replies
7
Views
5K
Replies
5
Views
762
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
2K
Replies
3
Views
776
  • Introductory Physics Homework Help
Replies
2
Views
1K
Back
Top