Mechanics Goldstein, chpt 1 exercise 11, Lagrangian of rolling disk

Burkay

Hi there,*
I want to reply to your force in this question. I hope I am not too late to answer :) since i didnt check the day of the post. To express the force you apply you must convert it to your degree of freedom. E.g. if dof is θ then it should be like F*r where r is the radius of the disk. If your dof is x, then it is simply x. Simply you must carry the Equilavent forces to your d.o.f. of the system.

Burkay

I checked your equation again. Since your equations give Force equilibrium, not moment. It is simply F, whatever your F is.