Using Lagrangian and Euler to Analyze the Falling Stick Problem

  • Thread starter Thread starter Raziel2701
  • Start date Start date
  • Tags Tags
    Falling Lagrangian
Click For Summary
SUMMARY

The discussion focuses on analyzing the falling stick problem using Lagrangian and Euler methods. The potential energy of the stick is expressed as mgL, while the kinetic energy comprises both rotational and translational components, represented by \(\frac{1}{2}I\omega^2\) and \(\frac{1}{2}mv^2\) respectively. The participant grapples with the degrees of freedom in the system, ultimately recognizing that the motion of the center of mass can be described by the angle of the stick. The potential energy is adjusted to mglcos(theta) as the stick falls.

PREREQUISITES
  • Understanding of Lagrangian mechanics
  • Familiarity with rotational dynamics and moment of inertia
  • Knowledge of kinetic and potential energy concepts
  • Basic grasp of degrees of freedom in mechanical systems
NEXT STEPS
  • Study the Lagrangian formulation of mechanics in detail
  • Learn about calculating moment of inertia for various shapes
  • Explore the concept of degrees of freedom in rigid body dynamics
  • Review resources on energy conservation in mechanical systems
USEFUL FOR

Students and educators in physics, particularly those studying mechanics and dynamics, as well as anyone interested in applying Lagrangian methods to real-world problems.

Raziel2701
Messages
128
Reaction score
0

Homework Statement


A meter stick stands on a frictionless surface and leans against a frictionless wall as shown. It is released to fall when it makes an angle of 1 degree from the vertical. Use Lagrange and Euler to find how long it takes the stick to fall to the ground.



The Attempt at a Solution


The potential of the stick will essentially just be mgL correct? Since the stick starts from an angle of 1 degree.

The Kinetic energy would have two components, a rotational and a translational. For rotation, I guess I'll just use [tex]\frac{1}{2}I\omega^2[/tex]. I guess I could look up the moment of inertia later on but I want to get the setup right.

For translational kinetic energy, when the stick falls, the center of mass of the stick falls down but it also moves horizontally, so there's an x and y component to the velocity so the KE would be [tex]\frac{1}{2}mv^2[/tex]

What concerns me is that v should be x-dot squared and y-dot squared but then it seems like I have too many variables for an object that has two(?) degrees of freedom.

How do I set this up?
 
Physics news on Phys.org
Ok I realized a few things that are very hard to grasp for me. Mainly, understanding how we can describe the problem requires such a feel for the problem that I request some links, or books that deal with this method(Lagrangian method).

So the center of mass describes a circle in its motion so the only degree of freedom is governed by the angle correct? The potential would also be different now, it should be mglcos(theta).

I'm going back to work on this, I'll come back if I need more help but I'd still like some more references to read up and study if you'd be so kind.
 

Similar threads

Replies
3
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
Replies
5
Views
1K
  • · Replies 95 ·
4
Replies
95
Views
7K
Replies
8
Views
2K
  • · Replies 6 ·
Replies
6
Views
1K
Replies
39
Views
4K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
3
Views
2K