A particle is moving in a circle of radius $R . \Lambda \mathrm{t} t=0$ its speed is $v_{0}$ and during its motion speed
varies as $\frac{d v}{d t}-\frac{-k v^{2}}{R}$ where $k$ is a positive constant. Find the speed of the particle: (a) after $1 \mathrm{sec}$; (b) after 1 revolution.