A car is travelling at $30m{s}^{-1}$ speed on a circular road of radius 300 m. If its speed is increasing at the rate of $4m{s}^{-2},$ then its acceleration is

Speed of car on circular road,
$\begin{array}{l}v=30m{s}^{-1}\\ r=300m\end{array}$ 
Centripetal acceleration, $a_c=\frac{v^2}{r}=\frac{{\left(30\right)}^2}{300}=3m^{-2}$
Tangential acceleration, $a_T=4m{s}^{-2}$   
Net acceleration on the car, $a=\sqrt{a_c^2+a_T^2}=\sqrt{3^2+4^2}=5m{s}^{-2}$