A spherically symmetric gravitational system of particles has a mass density
\[
\rho =
\begin{cases}
\rho_0 & \text{for } r \le R \\
0 & \text{for } r > R
\end{cases}
\]
where \(\rho_0\) is a constant. A test mass can undergo circular motion under the influence of the gravitational field of particles. Its speed \(v\) as a function of distance \(r\) \((0 < r < \infty)\) from the centre of the system is represented by:
Show Hint
Inside a uniform sphere, gravitational field is proportional to distance from the centre.