What is the linear velocity of a particle in uniform circular motion of radius $A$ and angular velocity $\omega$?

In uniform circular motion,which of the following statements is wrong?

The angular speed of the seconds needle in a mechanical watch is:

The figure below shows a body of mass $M$ moving with a uniform speed $v$ on a circular path of radius $R$. What is the change in acceleration when moving from point $P_1$ to $P_2$?

An annular ring with inner and outer radii $R_{1}$ and $R_{2}$ is rotating with a uniform angular speed $\omega$ about its central axis. The ratio of the centripetal forces experienced by two particles of equal mass $m$ situated on the inner and outer parts of the ring,$\frac{F_{1}}{F_{2}}$ is

$A$ particle is moving in a circle of radius $5 \,cm$ with uniform speed and completes the circle in $5 \,s$. What is the magnitude of linear acceleration?