$A$ uniform rod of length $l$ and density $\rho$ is revolving about a vertical axis passing through its one end. If $\omega$ is the angular velocity of the rod,then the centrifugal force per unit area of the rod is

• A
  $\frac{\rho \omega^2 l^2}{4}$
• B
  $\frac{\rho \omega^2 l^2}{12}$
• C
  $\frac{\rho \omega^2 l^2}{2}$
• D
  $\frac{\rho \omega^2 l^2}{8}$