A smooth wire is bent into the form of a helix the equations of which, in cylindrical coordinates, are z=a*beta and r=b , in which a and b are constants. The origin is a center of attractive force, , which varies directly as the distance, r. By means of Lagrange’s equations find the motion of a bead which is free to slide on the wire. Ok, so my variables are r, beta, and z, right? But what is the attractive force? Is it gravity? I need to know how to account for the attractive force in this problem in order to know what the potential energy V is, which is necessary to solve for L=K-V, and thus derive the equations of motions. Any ideas?