Thanks a lot for the help. It did help. Now I could see the bob of the pendulum swinging.

However, I would like to see the link as well. I would want to upload my file. But, I cannot

find any option to attach my file to this post. I am typing the code below.

Thanks a lot for the help once again.Please help me in animating the link as well. Could I just

use "Plottools[line]" in the place of "pointplot" in the code below?

Code:

eom := { (J+1/2*m*l^2)(diff(phi(t),t,t))+1/2*m*l*g*sin(phi(t)) = 0
         , D(phi)(0) = 0
         , phi(0) = Pi/4
       }:

integ := dsolve(eom, numeric):

f := tt -> plots:-pointplot(eval([[sin,-cos](phi(t))], integ(tt))):

plots:-animate(f
               , [t]
               , t=0..10
               , frames=100
               , scaling=constrained
               , view=[-1..1,-1..1]
               , symbol=circle
              );

Thanks a lot for the help. It did help. Now I could see the bob of the pendulum swinging.

However, I would like to see the link as well. I would want to upload my file. But, I cannot

find any option to attach my file to this post. I am typing the code below.

Thanks a lot for the help once again.Please help me in animating the link as well. Could I just

use "Plottools[line]" in the place of "pointplot" in the code below?

Code:

eom := { (J+1/2*m*l^2)(diff(phi(t),t,t))+1/2*m*l*g*sin(phi(t)) = 0
         , D(phi)(0) = 0
         , phi(0) = Pi/4
       }:

integ := dsolve(eom, numeric):

f := tt -> plots:-pointplot(eval([[sin,-cos](phi(t))], integ(tt))):

plots:-animate(f
               , [t]
               , t=0..10
               , frames=100
               , scaling=constrained
               , view=[-1..1,-1..1]
               , symbol=circle
              );