Respuesta :
The volume of the shell that you described would be:
[tex]dV=2L\pi r dr[/tex]
Now we can rewrite the given integral:
[tex]\lambda L=\int\rho dV=L\rho\int2\pi r dr \\ \lambda L =L\rho \pi r^2\\ \rho=\frac{\lambda}{\pi r^2}[/tex]
I have attached the picture explaining how we got the formula for the volume.
On the picture, I marked the rectangle. You can of this rectangle as the base, and the height would be the circumference of the cylinder.
[tex]dV=2L\pi r dr[/tex]
Now we can rewrite the given integral:
[tex]\lambda L=\int\rho dV=L\rho\int2\pi r dr \\ \lambda L =L\rho \pi r^2\\ \rho=\frac{\lambda}{\pi r^2}[/tex]
I have attached the picture explaining how we got the formula for the volume.
On the picture, I marked the rectangle. You can of this rectangle as the base, and the height would be the circumference of the cylinder.

Answer:
Given
dq=density*dv
q=lamda*I
Taking double integration
density=lamda/2*pi*r^2