Problem 1.112

$1.112 .$ A horizontal disc rotates with a constant angular velocity $\omega=6.0$ rad/s about a vertical axis passing through its centre. A small body of mass $m=0.50$ kg moves along a diameter of the disc with a velocity $v^{\prime}=50 \mathrm{~cm} / \mathrm{s}$ which is constant relative to the disc. Find the force that the disc exerts on the body at the moment when it is located at the distance $r=30 \mathrm{~cm}$ from the rotation axis.