kill(all);

r: tubolar mean radius
t: tubolar wall thickness

A : 2*%pi*r*t;

J : fullratsimp( 
        integrate( 
            integrate( 
                (rho*sin(phi))^2  *rho
                ,phi,0,2*%pi
            )
            ,rho,r-t/2,r+t/2 
        )
    );

Jp : fullratsimp( 
        integrate( 
            integrate( 
                rho^2  *rho
                ,phi,0,2*%pi
            )
            ,rho,r-t/2,r+t/2 
        )
    );

W : fullratsimp(J/(r+t/2));

Wp : fullratsimp(Jp/(r+t/2));