A motor car is travelling at 60 m/s on a circular road of radius 1200 m. It is increasing its speed at the rate of 4 $\mathrm{m}/{\mathrm{s}}^2$. The acceleration of the car is:

Tangential acceleration, ${\mathrm{a}}_{\mathrm{t}} = \mathrm{r\alpha } = 4 \mathrm{m}/{\mathrm{s}}^2$

Radial acceleration

    ${\mathrm{a}}_{\mathrm{t}} = {\mathrm{\omega }}^2\mathrm{r} = \frac{{\mathrm{v}}^2}{\mathrm{r}} = \frac{60\times 60}{1200} = 3$$\mathrm{m}/{\mathrm{s}}^2$

Hence, resultant acceleration of the car

a = $\sqrt{{{\mathrm{a}}_{\mathrm{t}}}^2+{{\mathrm{a}}_{\mathrm{r}}}^2} = \sqrt{4^2+3^2} = 5 \mathrm{m}/{\mathrm{s}}^2$