How can one verify that an object is undergoing rotation about a fixed axis?

$A$ rigid rod of length $\ell$ is sliding. At some instant,the position of the rod is as shown in the figure. End $A$ has a constant velocity $v_0$ along the $x$-axis. At $t = 0$,the rod is vertical with end $B$ at $y = \ell$. Which of the following statements is correct?

As shown in the figure,a small wheel is coaxially connected to a larger wheel of double its radius. The system rotates about a common axis. Strings $A$ and $B$ are attached to the wheels such that they do not slip. If $x$ and $y$ are the distances covered by $A$ and $B$ in the same time interval,then:

$A$ rod of mass $m$ and length $l$ is rotated about one of its ends with an angular velocity $\omega$. What is the tension in the rod at a distance $x$ from the axis of rotation?

$A$ rod of length $1 \ m$ is held vertically. What will be the speed of the other end when it touches the ground without slipping?

What is a rigid body?