3) Refer Fig Q3. A particle P moving in plane curvilinear motion is located by the polar coordinates shown. At a particular instant, following data are noted:
$r = 2m$, $\theta = 60^\circ$, $v_r = 3m/s$, $v_\theta = 4m/s$, $a_r = -10m/s^2$, $a_\theta = -5m/s^2$. For this instant calculate the radius of curvature of the particle. Use path co-ordinates.