The non-uniform circular motion of a body will change to uniform circular motion if:

A clock has a continuously moving second's hand of $0.1 \mathrm{m}$ length. The average acceleration of the tip of the hand (in units of $\mathrm{m} {\mathrm{s}}^{-2}$) is of the order of :

A mass $\text{m}$ moves in a circle on a smooth horizontal plane with velocity ${\mathrm{v}}_0$ at a radius ${\mathrm{R}}_0$ . The mass is attached to a string which passes through a smooth hole in plane as shown.

The tension in the string is increased gradually and finally $\text{m}$ moves in a circle of radius $\frac{{\mathrm{R}}_0}{2}$. The final value of the kinetic energy is:

Two blocks of masses $m$ and $2 \mathrm{m}$ connected by a massless string move along concentric horizontal circles on a horizontal frictionless table with $O$ as fixed point as shown in the figure. If $T$ is the period of motion, the tension in the longer part of the string is (Neglect the dimensions of the blocks when compared with the lengths of the string).