Hello,
I tried to derive equation of motion for simple pendulum using D'Alembert's principle. The file is attached herewith.
I got the equation as \ddot{\theta} - \frac{g}{l}\sin(\theta)=0.
However, if we use Lagrange equation of motion then we get
\ddot{\theta} + \frac{g}{l}\sin(\theta)=0.
Can anyone check the attached file and tell me if there is any mistake?
Thank you.
Hello Sir. Thank you for your reply.
According to the figure in the attached file, we have x = l sin (theta) and y = l cos(theta).
So, I am not getting your transformations x=l costheta and y=--lsintheta.
Dear Sir,
From your solution, the position of the pendulum you are taking is wrong the correct position will be x = l sin(theta) and y = - l cos(theta) because the pendulum is downward hence negative y-direction we have to take.
- Badges
- Science topic
- Similar topics
- Mathematical Sciences
- Control Theory
- Control Systems