A car travelling at a speed of $\text{30 km/h}$ is brought to a halt in $8$ m by applying brakes. If the same car is travelling at $\text{60 km/h}$, it can be brought to a halt with the same braking force in:

The correct option is D $32m$

At a car travelling at a speed of $30$km/h is brought to rest in a distance of $8$m by applying brakes if the same car is moving at a speed of $60$km/h then that it can be brought to rest with same brakes in:

$\frac{1}{2}m{v}^2=Fs$

on the doubling, the speed and the required distance will become $4$ times that is $s=4\times 8=32$m