The uniform slender bar of mass $m$ and length $l$ is centrally mounted on the shaft $A-A$, about which it rotates with a constant speed $\dot{\phi}=p .$ Simultaneously, the yoke is forced to rotate about the $x$ -axis with a constant speed $\omega_{0} .$ As a function of $\phi,$ determine the magnitude of the torque $M$ required to maintain the constant speed $\omega_{0} .$ (Hint: Apply Eq. $7 / 19$ to obtain the $x$ -component of $M .$