Initial Conditions Applied to a Lagrangian

Click For Summary
SUMMARY

The discussion focuses on applying initial conditions to a Lagrangian system involving a pendulum of length l and mass m2, attached to a mass m1 that slides without friction. The derived Lagrangian is given by $$L=\frac{1}{2}(m_{1}+m_{2})\dot{X}^{2}+m_{2}l\cos\theta\dot{\theta}\dot{X}+\frac{1}{2}m_{2}l^{2}\dot{\theta}^{2}+m_{2}gl\cos\theta$$. The initial conditions specified are $$\theta(0)=\theta_{0}<<1$$, $$\dot{\theta}(0)=0$$, $$X(0)=0$$, and $$\dot{X}(0)=0$$, which are essential for solving the motion equations for θ and X using the Euler-Lagrange equations.

PREREQUISITES
  • Understanding of Lagrangian mechanics
  • Familiarity with Euler-Lagrange equations
  • Basic knowledge of pendulum dynamics
  • Ability to manipulate differential equations
NEXT STEPS
  • Study the derivation of the Euler-Lagrange equations in detail
  • Learn about small-angle approximations in pendulum motion
  • Explore numerical methods for solving differential equations
  • Investigate the effects of varying mass ratios on pendulum dynamics
USEFUL FOR

Students and educators in physics, particularly those focusing on classical mechanics, as well as researchers interested in Lagrangian systems and their applications in dynamic analysis.

vs74043
Messages
2
Reaction score
0

Homework Statement



The scenario is a pendulum of length l and mass m2 attached to a mass of m1 which is allowed to slide along the horizontal with no friction. The support mass moves along in the X direction and the pendulum swings through the x-y plane with an angle θ with the vertical. After finding the Lagrangian and the Euler-Lagrange equations for each of the two variables X and θ, apply the conditions
$$\theta(0)=\theta_{0}<<1\text{ but greater than 0}\\
\dot{\theta}(0)=0\\
X(0)=0\\
\dot{X}(0)=0$$
to get the motion for θ and X.

Homework Equations


I have derived the Lagrangian of this to be
$$L=\frac{1}{2}(m_{1}+m_{2})\dot{X}^{2}+m_{2}l\cos\theta\dot{\theta}\dot{X}+\frac{1}{2}m_{2}l^{2}\dot{\theta}^{2}+m_{2}gl\cos\theta$$

The Attempt at a Solution

 
Last edited:
Physics news on Phys.org
Hello vs, :welcome:

Post needs some adjusting to the PF guidelines. What relevant equations do you have to continue this exercise ? What you mention now is an intermediate result (which I think is right, but I didn't check it - will do so if you show the steps :smile: ).
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
Replies
6
Views
4K
  • · Replies 21 ·
Replies
21
Views
5K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
6K