Race car A follows path abcde while race car $B$ follows path $12c34$ track. If each car has a constant speed corresponding to a normal acceleration of $8{\mathrm{ms}}^{-2}$. The tracks abcde and $2c3$ are semicircular track while tracks $1-2$ and $3-4$ are straight track. Point a and point $1$ are the starting points of race and point $4$ and point e are finishing points of the race. Choose the correct statements.

 

If the kinetic energy of a particle of mass $m,$ performing uniform circular motion in a circle of radius $r,$ is $E,$ find the acceleration of the particle.

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:

In the given figure, $a=15 \mathrm{m} {\mathrm{s}}^{-2}$ represents the total acceleration of a particle moving in the clockwise direction in a circle of the radius $R=2.5 \mathrm{m}$at a given instant of time. The speed of the particle is