A car moving with a speed of 40km/h can be stopped by applying the brakes after at least 2m.  If the same car is moving with a speed of 80km/h, what is the minimum stopping distance?

$$\begin{gathered} equation of motion, \\ {V}^2 = U^2 – 2 as---\left(1\right) \end{gathered}$$

$$\begin{gathered} Applying brakes is Deceleration; initial velocity = 40km/h;dis\tan ce S=2m;substitute in above equation, \\ {0}^2 = {\left(40\right)}^2 – 2a x 2---\left(2\right) \\ then initial velocity = 80km/h;dis\tan ce=?;substitute in equation\left(1\right), \end{gathered}$$

$$\begin{gathered} 0^2 = {\left(80\right)}^2 – 2a x d---\left(3\right) \\ divide equation \left(3\right) by equation \left(2\right) \\ d=8m=minimum stopping dis\tan ce \end{gathered}$$